You’ve used the “friendly number” 10 to help solve some

math problems.

Today you will need…..

• A pencil • Your math journal• A hundred’s chart

Karen’s calculator broke when she dropped it down the stairs.

Karen’s calculator broke when she dropped it down the stairs. On her math homework she had the problem 99 + 8.

Karen’s calculator broke when she dropped it down the stairs. On her math homework she had the problem 99 + 8. Karen doesn’t think that she can solve the problem without her calculator.

Karen’s calculator broke when she dropped it down the stairs. On her math homework she had the problem 99 + 8. Karen doesn’t think that she can solve the problem without her calculator. Can you suggest a way for her to think about the problem so that she can solve it without her calculator?

Karen’s calculator broke when she dropped it down the stairs. On her math homework she had the problem 99 + 8. Karen doesn’t think that she can solve the problem without her calculator. Can you suggest a way for her to think about the problem so that she can solve it without her calculator?

Share your ideas with a Share your ideas with a partner. Then we will take a partner. Then we will take a look a way she might be able look a way she might be able to think about this problem.to think about this problem.

Discuss with a partner how 10 can help solve the problems

below:

• 8 + 4

• 9 + 3

• 8 + 3

Think, Pair, Share

How could the number 100 help you solve some problems?

It is important to be able to tell how far a number is from 100. A hundreds chart

can help you.

How far is 99 from 100?

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70

71 72 73 74 75 76 77 78 79 80

81 82 83 84 85 86 87 88 89 90

91 92 93 94 95 96 97 98 99

So…what might be the solution to 99 + 8?1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70

71 72 73 74 75 76 77 78 79 80

81 82 83 84 85 86 87 88 89 90

91 92 93 94 95 96 97 98 99

How could make 10 and some more help you with this problem?

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70

71 72 73 74 75 76 77 78 79 80

81 82 83 84 85 86 87 88 89 90

91 92 93 94 95 96 97 98 99

1 842 3 75 6

Think

99 +8

is the same as

Make ten and some more is also like make a hundred and some more.

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70

71 72 73 74 75 76 77 78 79 80

81 82 83 84 85 86 87 88 89 90

91 92 93 94 95 96 97 98 99 100

1 42 3 75 6

Think

99 +8

is the same as

100 + 7

How far is 95 from 100? Use your hundreds chart if you would

like.

Discuss how this could this help you solve the problem 95 + 6?

How far is 97 from 100? Use your hundreds chart if you would

like.

Discuss how this could this help you solve the problem 97 + 4?

10 and 100 are not the only “friendly numbers”.

Can you think of ways you can use other “friendly numbers” to help

solve the problems below?

• 19 + 5

• 3 + 48

• 39 + 4

Write two addition problems that would make use of the friendly

numbers below?

60 20 70

40 80 50