Chhalaang se Pehle Dekho!

Class 7 Maths · Chapter 12: Point ke Aage Ek Aur Jhalak · NCERT Ganita Prakash section P2 4.4

Seekho

Prithvi Sooraj ka chakkar 365.2422 din mein lagaati hai, par calendar saal 365 din ka. Bacha 0.2422 din chhota lagta hai, par 100 saal mein 0.2422 × 100 = 24.22 din: mausam dheere-dheere calendar se door khisak jaayenge!

0.2422 × 100 = 24.22

Sudhaar 1: har chauthe saal ek din jodo (leap year). Tab chaar saal mein 4 × 365 + 1 = 1461 din, 4 × 365.2422 = 1460.9688 ke kareeb. Par 100 saal mein ab 100 × 365 + 25 = 36,525 din, jabki Prithvi ko 36,524.22 chahiye: humne zyaada sudhaar kar diya.

100 × 365 + 25 = 36,525

Sudhaar 2: sadi ke saal (100 se bhaag) leap year nahi. Ab 100 saal mein 24 × 366 + 76 × 365 = 36,524 din. 1000 saal mein 3,65,240 din, jabki 1000 × 365.2422 = 3,65,242.2: ab bhi 2.2 din kam.

24 × 366 + 76 × 365 = 36,524

Sudhaar 3: 400 se bhaag hone wala sadi ka saal phir bhi leap year. To 2000 leap year tha, par 1900 aur 2100 nahi. Chhote decimals, sadiyon se guna hokar, hamara calendar tay karte hain!

2000 leap · 1900, 2100 not leap

Explore: leap ya nahi?

1. Teeno niyamon se saal sort karo.

Yaad rakho

• Saal 365.2422 din ka, isliye calendar ko leap years chahiye.
• Leap year: 4 se bhaag, par sadi ke saal sirf 400 se bhaag hon to.

Quick check

Prithvi ko Sooraj ke 4 chakkar mein kitne din?

1. 1460.9688
2. 1461
3. 1460
4. 1464.9688

Socho

Teeno niyamon se 400 calendar saal mein kitne din? 400 × 365.2422 ke kitne paas?

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.