Posts Tagged ‘Division And Squaring’

Problems Based On Subtraction, Division And Squaring

Thursday, November 5th, 2009

TYPE 1: Instant Subtraction

Use the formula ALL FROM 9 AND THE LAST FROM 10 to perform instant subtractions.

Example 1: 1000 – 357 = 643

Step 1: Take each figure in 357 and subtract it from 9 and the last figure from 10.

1 0 0 0   –   3 5 7   =  6 4 3

(     9  –  3  = 6

9  –  4  = 5

10 –  7  = 3     )

So the answer is 1000 – 357 = 643

Example 2: 10,000 – 1049 = 8951

Step 1: Take each figure in 1049 and subtract it from 9 and the last figure from 10.

1 0 0 0 0   –   1 0 4 9   =  6 4 3

(     9  –  1  = 8

9  –  0  = 9

9  –  4  = 5

10  –  9  = 1  )

So the answer is 1000 – 357 = 643

TYPE 2: SQUARING NUMBERS ENDING WITH 5

Example 1: 752 = 5625

75 = 75 X 75

Step1: Multiply the first number 7, by the next preceding number, which is 8.

Thus, we have 7 X 8 = 56, which is the first part of the answer.

Step 2: The last part will be the square of 5, which is 25

Thus the answer for 752 is divided into 2 parts: 56 and 25 which when combined together gives 5625.

Type 3: DIVIDING A NUMBER BY 9

Example 1: 23 / 9

Step 1: The first figure of 23 is 2, thus the quotient is 2.

Step 2: The sum of the 2 digits 2 and 3 is 5, thus the remainder is 5.

Example 2: 43 / 9

Step 1: The first figure of 43 is 4, thus the quotient is 4.

Step 2: The sum of the 2 digits 4 and 3 is 7, thus the remainder is 7.

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