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How many 4-digit numbers have the last digit equal to the sum of the first two digits?
450.
(Note: "x" below signifies that this digit is temporarily being ignored)
This is true for:
10x1
11x2
12x3
13x4
14x5
15x6
16x7
17x8
18x9
So for the first eligible 1000 numbers there are 9 (when we disregard the third digit).
For the next 1000 (that is 2000 to 2999) there will be 8 (it is one less because the first digit is 2 and not 1)
This pattern will continue all the way through the 4 digit numbers, so that our answer is:
9+8+7+6+5+4+3+2+1 = 45.
However as "x" above (that we temporarily ignored) can be any digit we have to multiply this by 10 (as there are 10 digits). Therefore the answer will be 450!
What else can I help you with?
How many three digit numbers have the sum of their digits equal to 22?
21.
What two digit numbers whose two digits added together equal 42 and multiplied together equal 82?
Two (or four) digits added together cannot equal 42. Two-digit numbers multiplied together cannot equal 82.
How many three digit numbers is average of three digits equal to 2?
21
How many integers between 200 and 300 have the sum of their digits equal to 15?
Since the first integer of the 3-digit numbers must be 2, the sum of the second and the third digits would be 13.Since the largest digit is 9, the 3-digit numbers could be 249, 294, 258, 285, 267, and 276.Thus, there are 6 integers between 200 and 300 whose sum of their digits is 15.
What are Two nine digit numbers divided to equal pi?
No two numbers that can be completely written down with digits can be added, subtracted, multiplied, or divided to equal PI. If they could be divided to equal PI, then PI would be a rational number. But it isn't.
How many three digit numbers have the sum of their digits equal to 22?
21.
What two digit numbers whose two digits added together equal 42 and multiplied together equal 82?
Two (or four) digits added together cannot equal 42. Two-digit numbers multiplied together cannot equal 82.
How many three digit numbers is average of three digits equal to 2?
21
How many 5-digit numbers have digits whose product is equal to 4?
There are 15 of them.
What is a four digit number with ascending digits whose first two numbers have a difference of two the third digit is even and the sum of the first three digits equal the last digit?
1348.
How many 3 digits whole numbers whose sum is 3?
There are no 3-digit whole numbers whose digits sum to 3. The smallest 3-digit number is 100, and the largest is 999, but in neither case is the sum of the digits equal to 3.
How many 3 digit numbers have the sum of their digits equal to 5?
002+002+001=005
How many three digit numbers equal 17?
There are no three-digit numbers that equal 17. In fact, there are no numbers with more or less than two digits that equal 17. In fact, in the whole infinite supply of numbers, there is only one single number that equals 17. That number is . . . . . . . 17 .
What two prime numbers equal a 400 digit number?
I'm sure there are more than 2 prime numbers that are 400 digits long.
What is the formula to find number of three digit numbers such that sum of the squares of any two digits is equal to third digit?
N squared would be used to find the square root of a number or numbers. In order to find the number of three digit numbers such that the sum of the square results of any two digits are equal to the third digit the use of the formula (HOE)squared=Hsquared*10000+2HE*100+Esquared is needed.
How many 5 digit numbers containing two times the digit 6 can be formed from the digits 123456?
No digit that is 5 places long is equal to 6 times 2 other than 12.000
How many different positive three digit are having the product of their digits equal to zero?
This is only possible if one of the digits is equal to zero. There are 90 3-digit numbers with a zero in the 10's place, and 90 3-digit numbers with a zero in the 1's place - and 9 numbers that have both a zero in the 10's place and a zero in the 1's place; these would be counted double if you just add the first two. So, you get: 90 + 90 - 9 such numbers.
