STEPS

Choose a 2-digit number ending in 5.

Multiply the first digit by the next consecutive number.

The product is the first two digit: XX__.

The last part of the answer is always 25: __25.

Example

If the number is 35, 3 x 4 = 12 (first digit times next number) : 12__

The last part of the answer is always 25: __25.

So 35 x 35 = 1225

## Saturday, 11 October 2008

## Monday, 1 September 2008

### Squaring a 2-digit number ending in 4

Steps

take a 2 digit number ending in 4.

square the 4; the last digit is 6: ___6 (keep carry, 1).

multiply the first digit by 8 and add the carry (1); the secondnumber will be the next to the last digit: __X6 (keep carry).

square the first digit and add the carry: XX__.

Example

if the number is 34, 4 x 4 =16 (keep carry, 1); the last digit is ___6.

8 x 3 = 24 (multiply the first digit by 8), 24 + 1 = 25 (add the carry): the next digit is 5: __56. (keep carry, 2).

square the first digit and add the carry, 2: 1156.

so 34 x 34 =1156.

take a 2 digit number ending in 4.

square the 4; the last digit is 6: ___6 (keep carry, 1).

multiply the first digit by 8 and add the carry (1); the secondnumber will be the next to the last digit: __X6 (keep carry).

square the first digit and add the carry: XX__.

Example

if the number is 34, 4 x 4 =16 (keep carry, 1); the last digit is ___6.

8 x 3 = 24 (multiply the first digit by 8), 24 + 1 = 25 (add the carry): the next digit is 5: __56. (keep carry, 2).

square the first digit and add the carry, 2: 1156.

so 34 x 34 =1156.

## Friday, 29 August 2008

### Squaring a 2-digit ending in 3

Steps

take a 2-digit number ending in 3.

the last digit will be ___9.

multiply the first digit by 6: the second number will be the next to the last digit: __X9.

square the first digit and add the number carried from the previous step: XX__.

Example

if the number is 43, the last digit

is ___9.

6 x 4 = 24: __49.

4 x 4 = 16, 16 + 2 = 18 (add carry): 1849.

so 43 x 43 = 1849

take a 2-digit number ending in 3.

the last digit will be ___9.

multiply the first digit by 6: the second number will be the next to the last digit: __X9.

square the first digit and add the number carried from the previous step: XX__.

Example

if the number is 43, the last digit

is ___9.

6 x 4 = 24: __49.

4 x 4 = 16, 16 + 2 = 18 (add carry): 1849.

so 43 x 43 = 1849

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