Presentation on theme: "Opening Objective By the end of this PowerPoint you should be able to:"— Presentation transcript:
1 Opening Objective By the end of this PowerPoint you should be able to: Use divisibility rules to factor numbers.Divide two and three digit numbers by one and two digits numbersPerform division and see how its inverse is closely correlated to it.
2 There is an inverse relationship between multiplication and division. Content Slide #1There is an inverse relationship between multiplication and division.The equation 45 ÷ 5 = 9 has the inverse relationships following are also true: 5 x 9 = x 5 = 45Similar relationships exist for multiplication. The equation 3 x 7 = 21 has the relationships: 21 ÷ 3 = ÷ 7 = 3
3 BrainstormingThere are 960 3rd grade students in a school. The students are to be equally divided into 64 classes. How many students do we have in each class? If 15 x 64=960 then 64√960=?
4 Content Slide #2 Last digit is even The sum of the digits is divisible by threeThe last two digits form a sum that is divisible by fourThe last digit is zero or fiveNumber is divisible by both two and three
5 Content Slide #3Take the last digit, double it, and subtract it from the rest of the number. If you get an answer divisible by 7 (including zero), then the original number is divisible by seven. If you don't know the new number's divisibility, you can apply the rule again. Ex. Check to see if 203 is divisible by seven.double the last digit: 3 x 2 = 6subtract that from the rest of the number: = 14.check to see if the difference is divisible by 7: 14 is divisible by 7, therefore 203 is also divisible by sevenLast three digits form a number divisible by eightThe sum of the digits is divisible by nineThe numeral ends in zero
6 Content Slide #4The (sum of the odd numbered digits) - (sum of the even numbered digits) is divisible by 11.Ex = = = is divisible by 11The number is divisible by both tree and fourDelete the last digit from the number, then subtract 9 times the deleted digit from the remaining number. If what is left is divisible by 13, then so is the original number.The last four digits form a number that is divisible by 16
8 Content Slide #51. Divide 84 ÷ 6 is the problem. Look at the first number only in the dividend so the problem is 8 ÷ 6. The answer is 1. Write it above the 8.2. Multiply. 1 x 6 = 6. Write the number 6 under the 8.3. Subtract The answer is 2. Write it down under the 64. Compare what is left over after subtracting with the divisor. It must be less than the divisor, if not, then go back to step 1 and choose a larger number to multiple.5. Bring down the 4. Then go through steps 1 through 4 again. 24 ÷ 6 = 4. Multiple. Subtract. Compare. There is not another number to bring down. The final answer is ÷ 6 = 14.
9 Focused Listing Is 150 divisible by 2, 3, 4, 5, 6, 9 and 10? 150 is divisible by 2 since the last digit is 0.150 is divisible by 3 since the sum of the digits is 6 (1+5+0 = 6), and 6 is divisible by 3.150 is not divisible by 4 since 50 is not divisible by 4.150 is divisible by 5 since the last digit is 0.150 is divisible by 6 since it is divisible by 2 AND by 3.150 is not divisible by 9 since the sum of the digits is 6, and 6 is not divisible by 9.150 is divisible by 10 since the last digit is 0.
10 We’re at the end and you should be able to: Closing ObjectiveWe’re at the end and you should be able to:Use divisibility rules to factor numbers.Divide two and three digit numbers by one and two digits numbersPerform division and see how its inverse is closely correlated to it.