Question

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Explanation:

Problem 1: Subtract 18 from 42 using regrouping (expanded form)

Step 1: Expand 42 and 18

First, expand 42 into tens and ones: \( 42 = 40 + 2 \).
Then, expand 18 into tens and ones: \( 18 = 10 + 8 \).

But we can't subtract 8 from 2 in the ones place, so we need to regroup the tens in 42.
Regroup 40 (4 tens) as 30 + 10 (3 tens and 1 ten), then add that 1 ten (10) to the ones place:
\( 42 = 30 + (10 + 2) = 30 + 12 \).

Now, expand the regrouped 42: \( 42 = 30 + 12 \)
And 18 remains: \( 18 = 10 + 8 \)

Step 2: Subtract the ones and tens

Subtract the ones: \( 12 - 8 = 4 \)
Subtract the tens: \( 30 - 10 = 20 \)

Step 3: Combine the results

Add the results of the ones and tens subtraction: \( 20 + 4 = 24 \)

Problem 2: Subtract 37 from 94 using regrouping (expanded form)

Step 1: Expand 94 and 37

Expand 94 into tens and ones: \( 94 = 90 + 4 \)
Expand 37 into tens and ones: \( 37 = 30 + 7 \)

We can't subtract 7 from 4 in the ones place, so regroup the tens in 94.
Regroup 90 (9 tens) as 80 + 10 (8 tens and 1 ten), then add that 1 ten (10) to the ones place:
\( 94 = 80 + (10 + 4) = 80 + 14 \)

Now, expand the regrouped 94: \( 94 = 80 + 14 \)
And 37 remains: \( 37 = 30 + 7 \)

Step 2: Subtract the ones and tens

Subtract the ones: \( 14 - 7 = 7 \)
Subtract the tens: \( 80 - 30 = 50 \)

Step 3: Combine the results

Add the results of the ones and tens subtraction: \( 50 + 7 = 57 \)

Answer:

s:

1. \( 42 - 18 = \boldsymbol{24} \)
2. \( 94 - 37 = \boldsymbol{57} \)