Find the sum of 23 and 48 using mental math.

One number makes the equation true. Find the missing number.
⎕ + 23 = 49

Find the missing number.

Find the sum of 28 and 36 using mental math.

Here the concept of Break Apart Numbers is used where a number is divided in two parts to make addition easy. The concept of friendly numbers is also used so that it becomes easy for addition or subtraction purpose. So, the first correct step for finding the sum of 28 + 36 mentally is 64.

Find the number that makes the equation true.
18 + 32 = ⎕

Here the concept of Break Apart Numbers is used where a number is divided in two parts to make addition easy. The concept of friendly numbers is also used so that it becomes easy for addition or subtraction purpose. So, the first correct step for finding the sum of 18 + 32 mentally is 50.

Find the second addend of 34 to make a 10.

Then, the second addend will becomes 6 by adding 4 gives 10.

Which is not the correct step for finding the sum of 34 and 16.

Here the concept of Break Apart Numbers is used where a number is divided into two parts to make addition easy. The concept of friendly numbers is also used so that it becomes easy for addition or subtraction purpose. So, the first incorrect step for finding the sum of 34 and 16 mentally is 34 + 7 + 11.

Find the number that makes the equation true.
23 + 7 = ⎕

Here the concept of Break Apart Numbers is used where a number is divided in two parts to make addition easy. The concept of friendly numbers is also used so that it becomes easy for addition or subtraction purpose. So, the first correct step for finding the sum of 28 + 36 mentally is 30.

With the help of the image find the sum.

>>> Tens: 60 + 20 = 80
>>> Ones: 2 + 4 = 6
>>> Sum: 80 + 6 = 86

Find the missing ones or tens digits.
15 + 59 = ⎕4

15 + 59 = 74.

With the help of the image find the sum.

Tens: 30 + 10 = 40
Ones: 4 + 9 = 13
Sum: 40 + 13 = 53

Find 34 + 49.

***  So, 34 + 49 = 83
 

Find the missing ones or tens digits.
17 + 45 = 6⎕

>>> 17 + 45 = 62.

Find the missing number.

Since, the partial division of a number gives ones same as the digit in the one's place.
>>> 82 -> 80 + 2.

Find the partial sums:

Tens = 30 + 20 = 50
Ones = 5 + 4 = 9

Find the partial sum of the given place value block.

>>> Tens: 10 + 20 = 30
>>> Ones: 5 + 6 = 11