What this lesson shows
Round 38 and 47 to the nearest ten: 40 + 50 is about 90. Work out 85, and check it is close to the estimate.
The worked example
The lesson works this one step by step: 38 + 47. Then your kid tries one like it on paper.
The steps
- Round each number
- Add the tens for an estimate
- Add exactly
- Close to the estimate?
Helping at home
Round each number to the nearest ten and add the tens for an estimate. Then add exactly, tens and then ones. If the sum is far from the estimate, look for the slip.
If your kid gets stuck
Round each number to the nearest ten first.
Watch it with Lux
With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.
More in this unit
- Rounding to the nearest ten
- Which two tens?
- Look at the ones
- Halfway rounds up
- Adding by jumps
- Adding tens and ones
- Ten ones make a ten
- Subtracting tens and ones
- Trade a ten for ten ones
- Not always small from big
- Count up to subtract
- Two-step word problems
- A story for an equation
- Add four numbers
- Why trading works