Skill: Decompose a two-digit number

Explanation and Free Practice Resources

Decomposing a two-digit whole number means interpreting it as a number of tens and some ones, using the equivalence $1$ ten $= 10$ ones; for example, $47 = 4$ tens $+ 7$ ones $= 40 + 7$ . The learner connects the numeral, place-value representation, and additive equation, understanding that a digit’s value depends on its position rather than its face value. This scope is limited to whole numbers from 10 through 99, not larger-number generalizations or decimal decomposition.

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Detailed Explanation: Decompose a two-digit number

A two-digit number has:

a tens digit, which tells how many groups of 10
a ones digit, which tells how many extra ones

Remember: $1$ ten is the same as $10$ ones.

Example: Decompose $47$ .

Look at the tens digit: $4$ .
This means $4$ tens, or $40$ .
Look at the ones digit: $7$ .
This means $7$ ones, or $7$ .
Put the parts together:

47 = 4\text{ tens} + 7\text{ ones}

47 = 40 + 7

So, $47$ is 4 tens and 7 ones.

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Base 10 Blocks - Counting - Number to Picture, Tens and Ones

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