Amaze your students! With very little practice prior to class, you can multiply a pair of two-digit numbers in your head. Let them be impressed for a while; the adulation will feel great! Eventually though, they will demand that you show them the trick, even though it requires them to do math! This is a great follow-up activity to my companion lesson, “Area Multiplication”.
Includes journal prompts, homework master, extensions, Common Core standards addressed, and answer key.
to see state-specific standards (only available in the US).
Explain patterns in the number of zeros of the product when multiplying a number by powers of 10, and explain patterns in the placement of the decimal point when a decimal is multiplied or divided by a power of 10. Use whole-number exponents to denote powers of 10.
Recognize that in a multi-digit number, a digit in one place represents 10 times as much as it represents in the place to its right and 1/10 of what it represents in the place to its left.