Missing Numbers
Find the missing number: 9 + 8 = ___
17
Solve the doubles fact: 7 + 7 = ___
14
A pencil is 9 centimeters long. A book is 9 centimeters longer than the pencil. How long is the book?
18 centimeters
True or false: 6 + 6 has an even sum.
True. 6 + 6 = 12, and 12 is even.
Find the missing number: 18 = ___ + 6
12
Use 7 + 7 = 14 to help you solve 7 + 8. Explain your thinking.
15. Since 8 is one more than 7, add 1 to 14.
Sam’s skateboard is 81 centimeters long. His brother’s skateboard is 53 centimeters long. How much longer is Sam’s skateboard?
28 centimeters
John’s book is 18 centimeters long. It is 9 centimeters longer than his pencil. Which two equations represent the pencil’s length, p? A. 18 − 9 = p B. p + 18 = 9 C. 9 − p = 18 D. p + 9 = 18
A and D; the pencil is 9 centimeters long.
Find the missing number: 9 + 7 = 10 + ___. Explain how you know.
6. Move 1 from the 7 to the 9: 9 + 7 = 10 + 6.
Solve 12 − 5 using a strategy. Show or explain your thinking.
7. Example: 12 − 2 = 10, then 10 − 3 = 7.
A yard has four sides measuring 36 meters, 11 meters, 28 meters, and 24 meters. How many meters of fencing are needed to go all the way around it?
99 meters
Josh says, “All doubles facts have even sums.” Do you agree? Explain why and give an example.
Yes. Doubling a whole number makes two equal groups, so everything can be paired with nothing left over. Example: 7 + 7 = 14.
Find both missing numbers: 20 − 11 = ___ + 4. Then 13 − 9 = 11 − ___.
First blank: 5. Second blank: 7.
Solve 9 + 7 using two different strategies. Show or explain both.
Examples: make ten, 10 + 6 = 16; near doubles, 8 + 8 = 16
A rectangular garden is 18 meters long and 9 meters wide. How many meters of fencing are needed to go around it? If you have 60 meters of fencing, how much will be left?
54 meters of fencing; 6 meters left.
Tom read 39 pages last week and 54 pages this week. Sam read 27 pages last week and 69 pages this week. Who read more pages altogether? How many more?
Sam read 3 more pages. Tom: 93 pages; Sam: 96 pages.