Estimating with rounding You can round numbers up or down to make an estimate of a total. We have 31 red pens and 37 blue pens. About how many pens is that? Round the numbers to the nearest 10. 30 + 40 We have about 70 pens.
Which bill should I use to pay for lunch? pizza $8.20 juice $3.90 ice cream $6.50
That’s about $8 + $4 + $7. I should use a $20 bill.
