Squaring a 3-digit number with tens digits as 0

Squaring a 3-digit number with tens digits as 0.

Example 1. 307²
Step 1.

• Square units digits giving the last two digits of the answer. If the square is less than 10, pad it with a leading 0.
• 7² = 49

Step 2.

• Multiply the hundreds digit by the units digit, double it, giving the third and fourth digits of the answer. If the product is less than 10, pad the it with a leading 0.
• 3 x 7 x 2 = 42

Step 3.

• Square hundreds digits giving the leading digit / digits of the answer.
• 3² = 9

Step 4.

• Combine the digits calculated in Step 1 to Step 3 to obtain the final answer.

Answer. 94249


Example 2. 803²
Step 1. 3² = 09
Step 2. 8 x 3 x 2 = 48
Step 3. 8² = 64
Answer. 644809


Example 3. 609²
Step 1. 9² = 81
Step 2. 6 x 9 x 2 = 108 carry 1 over to be added to Step 3 leaving 08.
Step 3. 6² + 1 = 37
Step 4. Combine the digits worked out in Step 1 to Step 3 to obtain the final answer.
Answer. 370881