Multiple Multiple Digit Whole Numbers Subtitle

Estimate to Eliminate Take each number and round it to the HIGHEST place value 179 rounds to the nearest hundreds----200 28 rounds to the nearest tens---30 200 x 30 = 6000 Our answer should be close to 6000…. answer should be lower than 6000, but not to much lower. (100 x 30=3000)

Algorithm-set of instructions that leads to a predictable result Standard Algorithm Algorithm-set of instructions that leads to a predictable result This is the “way” we learned This is the most efficient way to multiply multiple digits by multiple digits. Multiply 8 by 9=72-record the 0 and “carry” the seven (above the tens place) Multiple 8 by 7=56 + 7=63-record the 3 and “carry” the 6 (above the hundreds place) Multiple 8 by 1=8 + 6= 14 Add your “sneaky” zero Multiply the 2 by 9=18-record the 8 and “carry” the 1 (above the tens place) Multiply 2 by 7=14 +1=15-record the 5 and “carry” the 1 (above the hundreds place) Multiply 2 by 1=2 +1=3 Add 1432 + 3580=5012

Partial Product Remember: numbers are made up of digits and those digits have value. (Digit x Place Value=Value). Multiply each place value by the bottom numbers place value.

Area Box (Rectangle Method) Expand each of the numbers by their place value. 179=(100 + 70 + 9) and 28 (20+8) Area is Length x width….well each box gets a value when you multiple the length by the width. For example, 20 x 100 = 2000 Add all the boxes (partial products) together to get the product