Janamdin Ka Jaadu (Date Trick) | Class 8 Maths Book 2 Ch 6

📘 Class 8 · Ganita Prakash Book 2Ch 6 · Algebra PlayPost 2 / 7⏱ 25–30 min

Janamdin Ka Jaadu (Date Trick) 🎂

IS POST MEIN

Pehle Yeh Aata Hai?Kahani Concept Deep Concept Examples Real Life Galti 10 MCQs FAQs Practice HOTS Olympiad Recap

✅ Pehle Yeh Aata Hai?

Yeh post shuru karne se pehle, in teen sawaalon ko 1 minute mein khud try kijiye:

100 × 4 + 26 = ?
5 × 4 × 5 = ?
291 − 165 = ?

Answers dekho

Teeno sahi? Badhiya! Pichhla post: Socho Ek Number.

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🎬 Kahani: Priya Ka Janamdin

Rohan ne Priya se kaha: “Apne janamdin ke mahine ko 5 se guna karo. 6 jodo. 4 se guna. 9 jodo. 5 se guna. Ab tareekh jodo. Jawab batao.”

Priya: “1390.” Rohan ne dil mein 165 ghataaye: 1225. “Tumhara janamdin 25 December hai!” 🎄

Priya hairaan. Chalo, algebra se dekhte hain yeh kaise hua!

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📖 Concept: 100M + D Ka Khel

Step 1: Mahina M, tareekh D

Kadam	Algebra	26 Jan (M = 1, D = 26)
× 5	5M	5
+ 6	5M + 6	11
× 4	20M + 24	44
+ 9	20M + 33	53
× 5	100M + 165	265
+ D	100M + 165 + D	291

Step 2: 165 ghatao

291 − 165 = 126 = 100M + D. WHY yeh kaam karta? D zyada se zyada 31, do digit ka. To aakhri do digit = D (26), aage ke digit = M (1). 26 January! ✅

Step 3: Priya ka 1390

1390 − 165 = 1225 → M = 12, D = 25 → 25 December.

Step 4: Ulta karke dekho

1269 − 165 = 1104 → 4 November.
394 − 165 = 229 → 29 February.
296 − 165 = 131 → 31 January.

Step 5: Apni trick banao

Kadam badlo, phir algebra se pata karo kya ghatana hai. Jaise × 5, + 3, × 20, + D → 100M + 60 + D → 60 ghatao. Shart: M ka guna aakhir mein 100 ho, taaki D ke liye do digit khaali rahein.

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🔐 Deep Concept: 100 Hi Kyun?

Agar M ka guna sirf 10 hota (10M + D), to gadbad hoti. Jaise 1 × 10 + 31 = 41 aur 3 × 10 + 11 = 41: 31 Jan aur 11 March dono 41! 😮

100 se guna karne pe M aur D ki “jagah” alag ho jaati hai, koi takkar nahi. Yahi place value ka jaadu hai. 🔐

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✏️ Solved Examples

Example 1 (Easy): 15 August ke liye trick ka jawab?

100 × 8 + 165 + 15 = 980.

WHY sahi hai? 980 − 165 = 815 → 8, 15 ✅

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Example 2 (Medium): Jawab 1006. Janamdin?

1006 − 165 = 841 → M = 8, D = 41. Par tareekh 31 se zyada nahi hoti! To jawab galat bataaya gaya.

WHY sahi hai? Check karna bhi trick ka hissa ✅

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Example 3 (NCERT style): 1269, 394, 296 ke janamdin.

4 Nov, 29 Feb, 31 Jan.

WHY sahi hai? Har ek − 165 ✅

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Rohan ka raaz: “165 ghatao, aakhri do digit tareekh, baaki mahina!” 🎉

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🏠 Real Life Mein

🎂 Party trick doston ke saath.
🔢 Place value: 100M + D jaise ID numbers (jaise roll no. = class × 100 + number).
🔐 Coding mein do cheezein ek number mein chhupaana.
🗓️ Date format MMDD bhi isi tarah.

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🧭 Kab Use Karein, Kab Nahi

Situation	Kya karein	Kyun
Jawab − 165	✅ 100M + D	Trick ka niyam
Aakhri do digit > 31	❌ Galat jawab	D ≤ 31
M ka guna 10	❌ Takkar	100 chahiye
Apni trick	✅ Algebra se constant	Wahi ghatao

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❌→✅ Worked Mistake

Sawaal: Jawab 410. Janamdin?

❌ Galat: “410 → 4 October.”

Galti kya hai? 165 ghatana bhool gaye ❌

✅ Sahi: 410 − 165 = 245 → M = 2, D = 45? 45 > 31, to yeh jawab mumkin hi nahi! Dost ne galti ki.

Yaad rakho: Pehle 165 ghatao, phir check karo.

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📝 10 MCQs

Q1. Trick ka antim roop?

(a) 100M + 165 + D

(b) 10M + D

(c) M + D

(d) 100D + M

Solution dekho

Sahi jawab: (a)

(a) sahi: Sahi ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Ulta.

Q2. 291 ka janamdin?

(a) 26 Jan

(b) 29 Jan

(c) 1 Feb

(d) 12 Jun

Solution dekho

Sahi jawab: (a)

(a) sahi: 126 ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Nahi.

Q3. 1390?

(a) 25 Dec

(b) 13 Sep

(c) 12 Dec

(d) 9 Mar

Solution dekho

Sahi jawab: (a)

(a) sahi: 1225 ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Nahi.

Q4. 1269?

(a) 4 Nov

(b) 12 Jun

(c) 11 Apr

(d) 10 Jan

Solution dekho

Sahi jawab: (a)

(a) sahi: 1104 ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Nahi.

Q5. 394?

(a) 29 Feb

(b) 3 Sep

(c) 22 Feb

(d) 9 Mar

Solution dekho

Sahi jawab: (a)

(a) sahi: 229 ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Nahi.

Q6. 296?

(a) 31 Jan

(b) 2 Sep

(c) 13 Jan

(d) 1 Mar

Solution dekho

Sahi jawab: (a)

(a) sahi: 131 ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Nahi.

Q7. 15 Aug ka jawab?

(a) 980

(b) 815

(c) 815 + 165 + 1

(d) 1015

Solution dekho

Sahi jawab: (a)

(a) sahi: 800 + 165 + 15 ✅
(b) galat: Bina 165.
(c) galat: Nahi.
(d) galat: Nahi.

Q8. 100 kyun?

(a) M aur D takraayein nahi

(b) Sundar

(c) Bada

(d) Rule

Solution dekho

Sahi jawab: (a)

(a) sahi: Sahi ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Wajah hai.

Q9. × 5, + 3, × 20, + D: kya ghatao?

(a) 60

(b) 165

(c) 3

(d) 100

Solution dekho

Sahi jawab: (a)

(a) sahi: 5M·20 = 100M, 3 × 20 = 60 ✅
(b) galat: Purani trick.
(c) galat: Nahi.
(d) galat: Nahi.

Q10. Jawab 1006 sahi?

(a) Nahi, D = 41

(b) Haan, 8 Aug

(c) Haan, 10 Jun

(d) Pata nahi

Solution dekho

Sahi jawab: (a)

(a) sahi: 841 → D 41 > 31 ✅
(b) galat: Nahi.
(c) galat: Nahi.
(d) galat: Pata hai.

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❓ FAQs (Bachchon Ke Asli Sawaal)

1. 165 kahan se aaya?

6 × 4 = 24, + 9 = 33, × 5 = 165.

2. D ek digit (jaise 5) to?

100M + 05: aakhri do digit 05 → 5.

3. Kya tareekh pehle aur mahina baad?

Steps badal ke ho sakta; algebra se banao.

4. Saal bhi?

Haan, 10000 jaise bade guna se; khud try karo!

5. Galat jawab kaise pakdein?

D > 31 ya M > 12 aaye.

6. 29 Feb?

Leap year mein hota hai; trick theek kaam karti.

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🏋️ Practice Zone (12 Sawaal)

Q1. Easy 2 October ka jawab?

Solution dekho

200 + 165 + 2 = 367.

Q2. Easy 26 January?

Solution dekho

291.

Q3. Easy Jawab 680?

Solution dekho

515 → 15 May.

Q4. Easy Jawab 1430?

Solution dekho

1265 → M = 12, D = 65? D > 31, galat jawab.

Q5. Medium 14 November?

Solution dekho

1100 + 165 + 14 = 1279.

Q6. Medium Jawab 1186?

Solution dekho

1021 → 21 October.

Q7. Medium Apni trick: × 10, + 7, × 10, + D. Kya ghatao?

Solution dekho

70.

Q8. NCERT style 1269, 394, 296 ke janamdin.

Solution dekho

4 Nov, 29 Feb, 31 Jan.

Q9. NCERT style Apna janamdin trick se nikaalo.

Solution dekho

Khud karo!

Q10. Medium Kya 31 April ho sakta? Trick kya degi?

Solution dekho

100 × 4 + 165 + 31 = 596 → 431. Trick to dega, par April mein sirf 30 din!

Q11. Medium × 5, + 1, × 20, + D: ghatao?

Solution dekho

20.

Q12. NCERT style 10M + D mein takkar dikhao.

Solution dekho

31 Jan aur 11 Mar dono 41.

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🧠 HOTS (Sochne Wale Sawaal)

Q1. Ek trick banao jo mahina, tareekh aur saal (2 digit) bataaye.

Solution dekho

10000M + 100D + Y: × 100, + D, × 100, + Y.

Q2. Agar dost “+ 9” bhool jaaye to?

Solution dekho

100M + 120 + D → 165 ghatane pe 45 kam aayega.

Q3. Kya trick 0 se shuru mahine pe?

Solution dekho

Mahine 1–12, to theek.

Q4. Jawab 3-digit ya 4-digit kab?

Solution dekho

M ≤ 8 to 3 digit (≤ 996); M ≥ 9 to 4 digit.

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🏆 Olympiad Corner

Q1. Kitne alag jawab mumkin (366 din)?

Solution dekho

366, har din alag.

Q2. Sabse chhota jawab?

Solution dekho

1 Jan: 100 + 165 + 1 = 266.

Q3. Sabse bada?

Solution dekho

31 Dec: 1200 + 165 + 31 = 1396.

Q4. Trick × 5, + 6, × 4, + 9, × 5 ki jagah × 25, + 33, × 4?

Solution dekho

100M + 132 + D: 132 ghatao.

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💗 CharuMam Motivation

Rohan ne place value aur algebra milaake ek jaadu bana diya! 🎂

Jo seekhte ho (place value, guna, algebra), use milaa ke naya kuch banao. Gyaan jodne se hi naya gyaan banta hai! 💡

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🟢 Master Recap

Trick: × 5, + 6, × 4, + 9, × 5, + D → 100M + 165 + D.
Jawab − 165: aakhri do digit = tareekh, baaki = mahina.
26 Jan → 291; 25 Dec → 1390.
100 se guna = M aur D ki alag jagah.
Apni trick: algebra se constant nikaalo.

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👉 Aage Kya?

Ab numbers ka pyramid: upar wala neeche ke do ka jod. Isme bhi algebra chhupa hai! 🔺

← Pichla: Post 1 — Socho Ek Number: Jaadu Ka Raaz 📚 Chapter 6 ke saare posts Agla: Post 3 — Number Pyramids →

Koi doubt? CharuMam AI Tutor se poochho, ya comment mein likho! 💬

✅ Pehle Yeh Aata Hai?

🎬 Kahani: Priya Ka Janamdin

📖 Concept: 100M + D Ka Khel

Step 1: Mahina M, tareekh D

Step 2: 165 ghatao

Step 3: Priya ka 1390

Step 4: Ulta karke dekho

Step 5: Apni trick banao

🔐 Deep Concept: 100 Hi Kyun?

✏️ Solved Examples

🏠 Real Life Mein

🧭 Kab Use Karein, Kab Nahi

❌→✅ Worked Mistake

📝 10 MCQs

❓ FAQs (Bachchon Ke Asli Sawaal)

🏋️ Practice Zone (12 Sawaal)

🧠 HOTS (Sochne Wale Sawaal)

🏆 Olympiad Corner

💗 CharuMam Motivation

🟢 Master Recap

👉 Aage Kya?

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