This lesson introduces the "99 multiplier" shortcut for multiplying whole numbers mentally. It works by annexing zeros to the multiplicand equal to the number of 9s in the multiplier, then subtracting the original multiplicand. Examples show 999×364 equals 364,000 minus 364, which is 369,636. The lesson aims to help students appreciate exploring multiplication and the multiplication operation.

1. Lesson 13<br />“THE 99 MULTIPLIER” SHORTCUT IN MULTIPLYING WHOLE NUMBER<br />Objectives<br />After this lesson, the students are expected to:<br />multiply whole numbers mentally;

2. appreciate exploring the world of multiplication;