98
To find the fifth number, you can use the formula for finding the average of a set of numbers. The sum of the 5 numbers is 82 * 5 = 410. The sum of the 4 known numbers is 80 * 4 = 320. Therefore, the fifth number can be found by subtracting the sum of the 4 known numbers from the sum of all 5 numbers: 410 - 320 = 90. So, the fifth number is 90.
90 x 70 = 6,300
It takes 4 90 degree angles to make a full circle
One relatively easy way to do this is to make a list of the first 10 squares: 1 4 9 16 25 36 49 64 81 100 and try to find 5 in a row that total to 90. 10 squared is 100. Too much. That can't be part of the answer. 1 + 4 + 9 + 16 + 25 is 55. Too small. 4 + 9 + 16 + 25 + 36 is 90. So the consecutive whole numbers are 2, 3, 4, 5, 6. The harder way but more fun way for a math teacher would be to make the middle number n. Then, we can set up an equation: (n-2)2 + (n-1)2 + n2 + (n+1)2 + (n+2)2 = 90 That expands to n2 - 4n + 4 + n2 -2n + 1 + n2 + n2 + 2n + 1 + n2 +4n + 4 = 90 Simplify to 5n2 + 10 = 90 5n2 = 80 n2 = 16 n = 4. The middle number of the 5 numbers is 4. The full set of consecutive whole numbers is 2, 3, 4, 5, 6. Doing the problem two ways is a great way to enhance understanding and to check your work.
There are 90 such numbers.
1, 2, 3, 5,
They are: 9+81 = 90
2 x 3 x 3 x 5
90
90
2 goes into both numbers 4 and 90 because 2 x 2 = 4 and 2 x 45 = 90.
109
As a product of its prime factors: 233*5 = 90
2 x 3 x 3 x 5 = 90
360
40