# Square a 3-digit number when the middle number is zero

You can quickly square a 3-digit number when the middle number (number in the tens place) is zero in about 4 seconds by following this trick.

Example #1

(604)2

Step 1

Square 6 and write it down on the left: 62 = 36

36

Step 2

Square 4 and write it down on the right side of 36: 42 = 16

36          16

Notice how we leave a space between 36 and 16.

Step 3

Multiply 2 by the product of the number in the ones place and the number in the hundreds place.

2 × 6 × 4 = 48

Step 4

Write 48 between 36 and 16 and you are done.

(604)2 = 364816

When working on step 2, if after squaring the digit in the ones place you get a number less than 10, just add a zero on the left. Example #2 below shows how to do this!

Example #2

(903)2

Step 1

Square 9 and write it down on the left: 92 = 81

81

Step 2

Square 3: 32 = 9

Since 9 is smaller than 10, put a zero on the left of it and write everything on the right side of 81.

81          09

Step 3

Multiply 2 by the product of the number in the ones place and the number in the hundreds place.

2 × 3 × 9 = 54

Step 4

Write 54 between 81 and 09 and you are done.

(903)2 = 815409

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