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2nd grade math · Unit 3: Adding and subtracting within 100

Trade a ten for ten ones

What this lesson shows

73 − 48: trade 1 ten to get 6 tens and 13 ones. Take away 4 tens and 8 ones: 25.

The worked example

The lesson works this one step by step: 73 − 48 = □. Then your kid tries one like it on paper.

The steps

  1. Not enough ones
  2. Trade a ten for 10 ones
  3. Take the ones, then the tens

Helping at home

Show the first number in tens and ones. When there are not enough ones to take, trade a ten for 10 ones. Take away the ones, then the tens.

If your kid gets stuck

Are there enough ones?

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.

See how Lux works

Standards

  • Common Core 2.NBT.B.5
    Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
Matches a standard in all 50 states and DCSee each state's code

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