Round up or round down?

The idea

Often an approximate value is enough instead of the exact number; rounding up gives an approximation more than the actual number, rounding down gives one less than it, and the situation decides which to use.

A rough number is enough

In 2011, the population of Chintamani town was 76,068.

To give a friend an idea of its size, what would you say?

• Exactly 76,068
• About 75,000
• About 1 lakh

Pick the better number

Each situation has the actual number and two rounded numbers. Pick the one that suits the situation.

Up, down, and the situation

An approximate value is often enough. Rounding up gives a number more than the actual number; rounding down gives one less. The situation decides which to use.

• Situation | Actual | Rounded to | Which way
• Sweets for everyone | 732 | 750 | up
• Price that sounds cheaper | ₹470 | ₹450 | down
• Quick idea of a population | 76,068 | 75,000 | down

Notes

An approximate value is often enough. Rounding up gives a number more than the actual; rounding down gives one less. The situation decides which to use.

Check yourself

The cost of an item is ₹470. Is ₹450 a rounded-up or a rounded-down number?

482 guests are coming to a wedding. The caterer should prepare food for…

A poster says “1 lakh people visited the book fair”, but exactly 99,999 came. What was done?

• Rounded up. Rounding up gives a number MORE than the actual. 450 is less than 470.
• Rounded down — correct. Yes! 450 is less than 470.
• 450 guests. That leaves 32 guests without food.
• 500 guests — correct. Yes! Round up, so that everyone is fed.
• Rounded up — correct. Yes! 1,00,000 is more than 99,999.
• Rounded down. 1,00,000 is more than 99,999, so it was rounded up.