Use mental math to calculate.
500-290
Use mental math to calculate.
1200 - 750
Use mental math to calculate.
600 + 1575
Use mental math to calculate.
2499 + 501
Use mental math to calculate.
399 + 299 + 199
Use mental math to calculate.
5000 - 1775
Use mental math to calculate.
5500 + 4500 + 2000
Use mental math to calculate.
7100-98
Use mental math to calculate.
2550 + 2450 + 2010
Explain how knowing 1000 + 2000 = 3000 can help you solve each problem.
a) A plane flew 999 km to one city and 2001 km to another city. What is the total distance the plane flew?
Explain how knowing 1000 + 2000 = 3000 can help you solve each problem.
b) A container holds 3000 mL of juice. 1001 mL of juice is poured out. How many millilitres are left in the container?
Use mental math to determine the missing number. Describe your strategy.
Use mental math to determine the missing number. Describe your strategy.
Use mental math to determine the missing number. Describe your strategy.
Use mental math to determine the missing number. Describe your strategy.
Use estimation to decide which answers are reasonable. Correct the unreasonable answers.
5679 + 2457 = 8136
Use estimation to decide which answers are reasonable. Correct the unreasonable answers.
987+304+723+815=1829
Use estimation to decide which answers are reasonable. Correct the unreasonable answers.
56767+45283=102050
Use estimation to decide which answers are reasonable. Correct the unreasonable answers.
3045 - 283 = 2762
Use estimation to decide which answers are reasonable. Correct the unreasonable answers.
12080 - 3479=7601
Use estimation to decide which answers are reasonable. Correct the unreasonable answers.
54213 - 24618 = 39595
In 2004, as part of the Kids Can Vote project, elementary and secondary students in Canada voted online in the federal election. The chart shows the voting results for Ontario.
a) Estimate how many students voted in the election. Show your work.
b) Estimate the difference in votes between the Liberals and the Greens. Show your work.
Estimate and calculate. Show your work.
145 + 289 + 365
Estimate and calculate. Show your work.
763+201+437+675
Estimate and calculate. Show your work.
999+999+999+999
Estimate and calculate. Show your work.
876+459+888+555
Estimate and calculate. Show your work.
457+235+608+236
Estimate and calculate. Show your work.
910+192+367+843
Calculate the perimeter of each shape. Show your work.
Calculate the perimeter of each shape. Show your work.
The chart shows the number of public schools in Toronto.
a) How many more schools are in the Toronto District Public School Board than in the Toronto Catholic District School Board?
b) Explain how you know that your answer is reasonable.
Calculate. Determine if your answers are reasonable. Show your work.
a) 10 000 - 476
b) 2345 - 906
c) 30 000 - 5619
d) 65 300 - 2366
e) 35 005 - 6521
f) 98 301 - 6725
An arena seats 20 000 people. The chart shows the number of people in each section.
a) How many empty seats are in the arena?
b) Explain how you know your answer is reasonable.
A powwow was attended by 12 459 people. Of these people, 1086 were participants. How many people were not participants?
Use mental math to calculate. Describe your strategy for two of your answers.
1.79 + 2.1
Use mental math to calculate. Describe your strategy for two of your answers.
3.50 + 2.25
Use mental math to calculate. Describe your strategy for two of your answers.
6.79 + 2.21
Use mental math to calculate. Describe your strategy for two of your answers.
6.99 + 3.25
Use mental math to calculate. Describe your strategy for two of your answers.
6.00 - 2.75
Use mental math to calculate. Describe your strategy for two of your answers.
10.00 - 4.99
Use mental math to calculate. Describe your strategy for two of your answers.
6.25 - 1.98
Use mental math to calculate. Describe your strategy for two of your answers.
4.000 - 1.999
Madison used a $20 bill to pay for a $1.96 drink and a $3.55 sandwich. Use mental math to calculate the change she received. Show your work.
Joshua’s height was 1.655 m on his 12th birthday and 1.800 m on his 13th birthday. Use mental math to calculate how much he grew in that year. Show your work.
Calculate. Determine if your answers are reasonable. Show your work.
1.45 + 2.38
Calculate. Determine if your answers are reasonable. Show your work.
6.666 + 7.77
Calculate. Determine if your answers are reasonable. Show your work.
15.099 + 3.771
Calculate. Determine if your answers are reasonable. Show your work.
0.765 + 0.238
Calculate. Determine if your answers are reasonable. Show your work.
3.457 + 0.9
Calculate. Determine if your answers are reasonable. Show your work.
3.55 + 4.8 + 2.089
What is the total mass of the rice?
Rice bag 1 - 0.876 kg
Rice bag 2 - 1.248 kg
a) What was the total precipitation in Seymour Fall, B.C., in January and February?
b) How much more precipitation is needed in March to equal 1 m ?
Calculate. Show your work.
1.00 - 0.65
Calculate. Show your work.
2.000 - 0.877
Calculate. Show your work.
10.000 - 4.762
Calculate. Show your work.
2.145 - 0.9
Calculate. Show your work.
4.666 - 1.999
Calculate. Show your work.
32.085 - 15.396
Use addition to check one answer in Question 18.
Show your work.
The diagram shows the boundaries of a nature park. Amelia is at sign 1. She wants to see the beaver dam at sign 4.
a) How much farther will she have to walk along the park boundaries than along the road?
b) Are your calculations reasonable? Explain.