lightning arithmetic

Squaring Quickly

Posted on June 29, 2019 by Samuel Nunoo

You may have seen the Fun Fact on squares ending in 5; Here’s a trick that can help you square ANY...

Posted on June 26, 2019 by Samuel Nunoo

Here’s a quick way to square numbers between 40 and 60. You know the squares of 40, 50, and 60,...

Posted on June 26, 2019 by Samuel Nunoo

Give me any 2 digit number that ends in 5, and I’ll square it in my head! 452 = 2025 852 = 7225, etc....

Posted on June 26, 2019 by Samuel Nunoo

You have all learned that a2 – b2 = (a + b)(a – b) But perhaps you haven’t thought about how to...

Posted on June 26, 2019 by Samuel Nunoo

Multiplication by 11 is easy! To multiply by a 2-digit number add the two digits and place the sum in...