Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 14 Properties and Mental Math
Transcript
14 Properties and Mental Math 1 Compatible Numbers pairs of numbers that can be computed easily. 2 Examples of compatible numbers 25 + 18 + 75 = _______ 50 + 25 + 47 + 25 + 100 = _______ 7 + 5 + 2 + 3 + 8 + 5 + 9 = _______ 30 + 40 + 50 + 70 + 50 + 37 = _______ 3 Patterns: Multiplication - When multiplying numbers that end in zeros, multiply the non-zero parts and annex one zero to your answer for each zero in the problem. Examples 20 x 700 = _______ 400 x 300 = _______ 30 x 5,000 = _______ 4 Patterns: Division - When dividing numbers that end in zeros, subtract the number of zeros in the divisor from the number of zeros in the dividend to find the number in the quotient. Examples 56,000 ÷ 70 = _______ 360,000 ÷ 600 = _______ 8,100 ÷ 900 = _______ 200,000 ÷ 40 = _______ 5 Practice 60 x 70 = _______ 63,000 ÷ 90 = _______ 100 x 300 = _______ 3,800 ÷ 20 = _______ 15,000 x 20 = _______ 750,000 ÷ 2,500 = _______ 6 Commutative and Associative Properties 7 The Commutative Property says that the order that you add OR multiply two numbers doesn't matterĶ¾ you still get the same answer Examples: Addition: 4 + 5 = 9 and 5 + 4 = 9. You get the same sum either way! Multiplication: 3 x 2 = 6 and 2 x 3 = 6 product either way! You get the same ***********Warning************ This does not work for subtraction or division!!! 8 9 The Associative Property says that you can group the numbers in any way and still get the same answer. We use parentheses to group numbers. We always do the operation in the parentheses first. Examples: and Addition: (4 + 5) + 2 = 11 get the same sum either way! 4 + (5 + 2) = 11. You Multiplication: (3 x 2) x 1 = 6 and the same product either way! 3 x (2 x 1) = 6 You get 10 11 Identity and Distributive Properties 12 Identity Property of Addition The identity element for addition is _______ If you add ______ to any number you still get that number. 4+0=4 0+5=5 Identity Property of Multiplication The identity element for multiplication is _______ If you multiply any number by ______ you still get that number. 6x1=6 13 14 The Distributive Property says that you can "distribute" (give) the number on the left (the multiplier) to the numbers on the right (the addends) and still get the same answer. 15 Examples Using the Distributive Property to Multiply 16 17 18
