WORD PROBLEMS WITH MENTAL MATH

Problem 1 :

For recess, 77 students chose to play outside and 19 students chose to play in the gym. How many students were playing at recess altogether ?

Solution :

Students chose to play outside for recess = 77

Students chose to play in the gym = 19

Total students playing at recess = students chose to play outside for recess + students chose to play in the gym

= 77 + 19

The nearest value of 77 is 80

= 77 + 3 + 16

= 80 + 16

= 96

Hence, 96 students were playing at recess altogether.

Problem 2 :

Five of the twelve students had no homework to take home on Friday. How many students had homework to take home ?

Solution :

Number of students = 12

No homework to take home on Friday = 5 students

Students had homework to take home = number of students - no homework to take home on Friday 

= 12 - 5

= 7

So, 7 students had homework to take home.

Problem 3 :

The surf shop had forty-two surfboards. The shop received a shipment with seventeen more surfboards. How many surfboards were at the surf shop ?

Solution :

Number of surfboards = 42 

Shop received a shipment = 17 surfboards

= 42 + 17

= 59

So, 59 surfboards were at the surf shop.

Problem 4 :

Machiko saw four grasshoppers in her backyard on Monday. On Tuesday she saw some more grasshoppers. She saw a total of eleven grasshoppers on those two days. How many grasshoppers did she see on Tuesday ?

Solution :

Monday = 4 grasshoppers

Tuesday = some more grasshoppers

Total grasshoppers = 11

Number of grasshoppers, she see on Tuesday = 11 - 4

= 7

So, 7 grasshoppers did she see on Tuesday.

Problem 5  :

Multiple Choice If x – 7 = 2, then which of these is not true ?

A.  7 - x = 2     B. x – 2 = 7     C. 2 + 7 = x    D.  x = 7 + 2

Solution :

Given, x – 7 = 2

It can be written as x = 2 + 7 or x = 7 + 2.

Then also 2 is shifting to the right hand side. So, x - 2 = 7.

But x - 7 = 2 we cannot written as 7 - x = 2.

So, option A. is correct.

Problem 6 :

A piano has 36 black keys and 52 white keys. Does a piano have more black keys or white keys ? How many keys does a piano have altogether ?

Solution :

Black keys = 36

White keys = 52

Total keys = Black keys + White keys

= 36 + 52

Total keys = 88

Standard piano keyboard has 88 keys with the natural.

Problem 7 :

The Helman family took a 745-mile car trip to visit relatives. The trip took three days because they made stops to sightsee each day. On the first day, they traveled 320 miles, and on the third day, they traveled 220 miles. How many miles did they travel on the second day ? Explain why your answer is reasonable.

Solution :

Total miles = 745

Number of days = 3

First day = 320 miles

Second day = ?

Third day = 220 miles

Second day = total miles - first day - third day

= 745 - 320 - 220

Second day = 205

So, 205 miles did they travel on the second day.

Problem 8 :

A chimpanzee weighs about 150 pounds. A gorilla weighs about 450 pounds. Which animal weighs more ? About how much more does it weigh ?

Solution :

Chimpanzee weighs = 150 pounds

Gorilla weighs = 450 pounds

So, gorilla is highest weighs.