NCERT Solutions Class 6th Maths Chapter – 1 Knowing Our Numbers All Examples

Example 1. Population of Sundarnagar was 2,35,471 in the year 1991. In the year 2001 it was found to be increased by 72,958. What was the population of the city in 2001?

Solution –

Population of the city in 2001
= Population of the city in 1991 + Increase in population
= 2,35,471 + 72,958
Now, 235471 + 72958 = 308429

Salma added them by writing 235471 as 200000 + 35000 + 471 and 72958 as 72000 + 958. She got the addition as 200000 + 107000 + 1429 = 308429. Mary added it as 200000 + 35000 + 400 + 71 + 72000 + 900 + 58 = 308429

Answer – Population of the city in 2001 was 3,08,429.
All three methods are correct.

Example 2. In one state, the number of bicycles sold in the year 2002-2003 was 7,43,000. In the year 2003-2004, the number of bicycles sold was 8,00,100. In which year were more bicycles sold? and how many more?

Solution –

Clearly, 8,00,100 is more than 7,43,000. So, in that state, more bicycles were sold in the year 2003-2004 than in 2002-2003.
Now, 800100 – 743000 = 057100

Check the answer by adding
743000 + 57100 = 800100 (the answer is right)

Can you think of alternative ways of solving this problem?
Answer – 57,100 more bicycles were sold in the year 2003-2004.

Example 3. The town newspaper is published every day. One copy has 12 pages. Everyday 11,980 copies are printed. How many total pages are printed everyday?

Solution –

Each copy has 12 pages. Hence, 11,980 copies will have 12 × 11,980 pages. What would this number be? More than 1,00,000 or lesser. Try to estimate.

Now, 11980 × 12 = 1,43,760
23960 + 119800 = 1,43,760

Answer – Everyday 1,43,760 pages are printed.

Example 4. The number of sheets of paper available for making notebooks is 75,000. Each sheet makes 8 pages of a notebook. Each notebook contains 200 pages. How many notebooks can be made from the paper available?

Solution –

Each sheet makes 8 pages.
Hence, 75,000 sheets make 8 × 75,000 pages,
Now, 75000 × 8 = 600000

Thus, 6,00,000 pages are available for making notebooks.
Now, 200 pages make 1 notebook.
Hence, 6,00,000 pages make 6,00,000 ÷ 200 notebooks.
Now, 200 ÷ 600000 = 3,000
The answer is 3,000 notebooks.