Decimals ka Multiplication

Class 7 Maths · Chapter 12: Point ke Aage Ek Aur Jhalak · NCERT Ganita Prakash section P2 4.2

Seekho

Ek pen ₹9.5 ka. Paanch pen 9.5 + 9.5 + 9.5 + 9.5 + 9.5 = ₹47.5. Fractions mein: 95/10 × 5 = 475/10 = 47.5. 12.5 km prati litre chalne wali gaadi 7.5 litre mein 12.5 × 7.5 = 125/10 × 75/10 = 9375/100 = 93.75 km.

12.5 × 7.5 = 93.75

Niyam: points hataakar guna karo, phir guna-phal mein dono numbers ke milaakar utne decimal sthaan. 596 × 248 = 147808, to 5.96 × 24.8 mein 2 + 1 = 3 sthaan: 147.808. Aur 5.8 × 1.24: 58 × 124 = 7192, 3 sthaan, to 7.192.

5.96 × 24.8 = 147.808

Kyun chalta hai: decimals 10, 100, 1000 … par fractions hain, aur denominators ka guna unke zero jodta hai: 10 × 100 = 1000. Neel school tak 0.827 km jaata hai, to din mein 0.827 × 2 = 1.654 km, aur 6 din mein 9.924 km.

1.654 × 6 = 9.924

Bada ya chhota? 2.25 × 8 = 18 dono se bada; 0.25 × 8 = 2 beech mein; 0.25 × 0.8 = 0.2 dono se chhota. Fractions jaisa: 0 aur 1 ke beech wale se guna chhota karta hai. Aur 56.50 × 2.250 wahi hai jo 56.5 × 2.25: point ke baad ant ke zero kuch nahi badalte.

0.25 × 0.8 = 0.2

Explore: 1 se kam?

Poora hisaab kiye bina guna-phal sort karo.

Yaad rakho

Bina point guna karo; guna-phal ke decimal sthaan = dono ke sthaanon ka jod.
0 aur 1 ke beech ka guna-khand guna-phal ko doosre number se chhota karta hai.

Quick check

18 × 12 = 216. 0.18 × 0.12 kya hai?

0.0216
0.216
2.16
0.00216

Answer

0.0216. 2 + 2 = 4 decimal sthaan: 0.0216.

Socho

Dukaan copiyan ₹23.6 mein khareedti aur ₹30 mein bechti hai. 50 copiyon par laabh?

Ek answer

Prati copy laabh = 30 − 23.6 = ₹6.4. 50 copiyon par: 6.4 × 50 = ₹320.

Practice

Teen levels (easy, medium, hard) ke naye sawaalon se practice karo, kuch hands-on, hints aur hal ke saath. Topic poora karne ke liye pichhle 5 mein se 4 sahi karo.