Using Mental Math to Divide
720 / 90 =
8
Use compatible numbers or rounding to divide.
1,769 / 23 =
1,769 = 1,800 23 = 20
1,800 / 20 = 90
9,345 / 5=
1,869
675 / 27 =
25
A county has 88 schools. The county received 992 new computers. Are there enough computers so that each school can get 11 new computers?
992/ 88 = 11 r 14. Each school will get 11 computers. There will be 14 leftover.
320 / 40 =
8
Use compatible numbers or rounding to divide.
516 /48 =
516 = 500 48 = 50
500 / 50 = 10
3,476 / 8=
434 r 4
780 / 39 =
20
There are 347 students going on a field trip. Each bus holds 44 students. If each bus costs $95, is the total cost of the buses more than 1,000.
No, 347 / 44 = 7 r 39, so they will need 8 buses.
8 x $95 = $760; $1000 > $760 so they will have enough money or $95 rounds to $100. $1000/$100 = 10; 10 x 44 = 440 students
24,000 / 80 =
300
Use compatible numbers or rounding to divide.
5,634 / 72 =
5,634 = 5,600 72 = 70
5,600 / 70 = 80
64,895 / 5 =
12,979
2,014/ 11=
183 r 1
A caravan crossed 1,378 miles of desert in 85 days. It traveled 22 miles on the first day and 28 miles on the second day. If the caravan traveled the same number of miles on each of the remaining days, how many miles did it travel on each of those days.
22 + 28 = 50 miles; 1,378 - 50 = 1,328 miles; 1,328/83 = 16 miles each day
49,000 / 70=
700
Use compatible numbers or rounding to divide.
3,514 / 58 =
3,514 =3,000 or 3,500 or 3,600 (cn)
58 = 60 or 50 (cn)
3,500 / 50 = 70 (cn) or 3,600 / 60 = 60 (cn);
0 3,000 / 60 = 50
12,464 / 4
3116
5,123 / 29 =
176 r 19
A tropical storm has been moving at 15 miles per hour for the past two days. Bess recorded that the storm moved 135 miles yesterday and 75 miles today. For how many hours has Bess been keeping track of the storm?
135 / 15 = 9 hours; 75/15= 5 hours; 9 + 5 = 14 hours
Which expressions has a quotient of 400?
A. 800 / 2
B. 8,000 / 2
C. 8,000 / 20
D. 80,000 / 20
A, C
Mr. McDonald's farm is 593 acres. He divides the farm into 32 equal parts. Which is the best estimate of the number of acres in each part?
A. 10 acres
B. 20 acres
C. 100 acres
D. 200 acres
593 = 600 32 = 30
600 / 30= 20 acres; B
Two fishermen caught 238 pounds of fish. They wanted to divide the catch evenly between them. How many pounds of fish will each fisherman receive?
119
Which quotient will be larger? Explain how you can tell without dividing.
3,444 / 42 = 4,368 / 42 =
4,368 / 42 will have a greater quotient because 4,368 > 3,444.
A parking garage has 6 levels. Each level has 15 rows. Each row has the same number of parking spaces. There are 2,250 parking spaces in all. How many parking spaces are in each row.
2,250 / 6 = 375; 375/15 = 25 in each row