Add the digits together. The sum of the digits of 23 is 5.
Any number using each of the digits once will be a multiple of 3: eg 1597864302
34.
Possibility of two digit no whose sum is 9 18,27,36,45,54,63,72,81 Now add 9 to each no mentioned above 27,36,45,54,63,72,81,90 See after third comma 45 and 54. Reverse of 45 is 54. 54 is 9 more than the no 45. So 45 is original
Possibility of two digit no whose sum is 7 16,25,34,43,52,61 Now subract 27 to each no mentioned above -9,-2,7,16,25,34 See after 4th comma 52 and 25.reverse of 52 is 25. That no 25 is 27 less than 52. Original no is 52;new no is 25
The last digit is always the estimated digit in a number
Add the digits together. The sum of the digits of 23 is 5.
Any number using each of the digits once will be a multiple of 3: eg 1597864302
Possibility of two digit no whose sum is 8 17,26,35,44,53,62,71 Add 18 with above no each output will be 35,44,53,62,71,80,89 See after second comma 35 and 53. If you add 18 with 35. 53 will come if you reverse it 35. 35 is
This problem can be solved by applying the counting principle to digits in consecutive page numbers. To begin, we need to separate numbers into their numbers of digits in order to multiply the page numbers to find the number of digits needed to express them. Assuming that your book begins on page 1, there are 9 page numbers having one digit only (counting principle: 9 - 1 + 1 = 9). Since each of these pages is numbered with one digit, the number of digits used is 9 so far. Continue with the pages each numbered with two digits. These are pages 10-99, comprising 90 pages (99 - 10 + 1 = 90). Every page number multiplied by 2 digits each is 180. With the 9 digits coming from single-digit pages, the number of digits used so far is now 189. We can continue in the same manner for pages expressed with three digits, 100-999, but having 435 (624 total - 189 so far = 435) digits left, we probably won't be able to get through all the three-digit numbers. Also, a book is likely to have under a thousand pages. To find out how many pages are left, we divide the number of digits left by the number of digits needed for each page: 435/3 = 145 pages left. Since 145 pages only account for the pages numbered with three digits each, we need to add pages numbered with one and two digits each in order to find the total number of pages. Before 145 pages began to be accounted for, we had accounted for the digits of 99 pages (each numbered using one or two digits each), so the total number of pages is 99 + 145 = 244.
100000 2847239582
It is the number of combinations of four numbers where the number of available digits starts at 10 and reduces by 1 each time.
You had me until "product." The product of 4 digits can't be prime.
45
26
You need to add up the number of digits to the right of the decimal to find the number of digits in the answer. If the first factor has 2 digits to the right of the decimal point and the second factor has 3, the final answer will have 5 digits to the right of the decimal point.
There are about 10-11 digits in a number
Possibility of two digit no whose sum is 9 18,27,36,45,54,63,72,91 Now add 9 to each no mentioned above 27,36,45,54,63,72,91,100 See after third comma 45 and 54. If you reverse 45 it will be 54. which is 9 more than 45. So original no is 45