Week 8MondaySubtracting Tens (Mental Math)
1Subtract 10

When you subtract 10, only the tens digit changes. The ones stay the same.

53 - 10 =

75 - 10 =

87 - 10 =

42 - 10 =

2Subtract Multiples of 10

Subtract the tens. Keep the ones.

54 - 20 =

86 - 30 =

88 - 10 =

83 - 20 =

3Number Line Jumps

Use the number line. Mark jumps of 10 backward from the first number.

75 - 30 =

70
80
90
100
110
120
130

Mark jumps of 10 backward from 75

87 - 40 =

80
90
100
110
120
130
140

Mark jumps of 10 backward from 87

4Number Talk: Which Difference is Bigger?

Number Talk — Which difference is bigger? Explain WITHOUT calculating.

75 - 20 or 75 - 40

My thinking:

86 - 30 or 86 - 10

My thinking:

5Challenge: Three Numbers

Challenge — Subtract all the tens first, then all the ones.

95 - 30 - 20 =

83 - 50 - 10 =