Not all of them are.
There are 282 such numbers.
13
Best way to work this out: find the highest number below 10,000 that is divisible by 7 (9,996) and divide that by 7 (1,428). 1,428 is the amount of one-, two-, three- and four-digit numbers divisible by 7. Now find the number of one-, two- and three-digit numbers divisible by 7 (which is 994/7 = 142) and subtract this number from 1,428, giving us 1,286.
8,888,888
1, 2, 4, 5, 7, 8
Not all of them are.
To find the least 4-digit number divisible by 2, 3, 4, 5, 6, and 7, we need to find the least common multiple (LCM) of these numbers. The LCM of 2, 3, 4, 5, 6, and 7 is 420. The smallest 4-digit number divisible by 420 is 1050. Therefore, 1050 is the least 4-digit number divisible by 2, 3, 4, 5, 6, and 7.
48. Assuming no digit can be used more than once, the two digit numbers divisible by 4 are: 16, 36, 48, 56, 64, 68, 84, 96 8 of them. For any number to be divisible by 4, only the last two digits need be divisible by 4; so for three digit numbers, each of the two digit numbers above can be preceded by any of the remaining 5 digits and still be divisible by 4. → 5 x 8 = 40 three digit numbers are divisible by 4 → 40 + 8 = 48 two or three digit numbers made up of the digits {1, 3, 4, 5, 6, 8, 9} are divisible by 4. If repeats are allowed, there are an extra 2 two digit numbers (44 and 88) and each of the two digit numbers can be preceded by any of the 7 digits, making a total of 7 x 10 + 10 = 80 two and three digits numbers divisible by 4 make up of digits from the given set.
There aren't any digits between 6 and 7 that are divisible by 4. There aren't any whole numbers between 6 and 7, period.
There are 282 such numbers.
13
The smallest 3-digit multiple of 7 is 105 = 15*7 The largest 3-digit multiple of 7 is 994 = 142*7 So there are 142-14 = 128 3-digit multiples of 7, ie 128 3-digit numbers that are divisible by 7.
Best way to work this out: find the highest number below 10,000 that is divisible by 7 (9,996) and divide that by 7 (1,428). 1,428 is the amount of one-, two-, three- and four-digit numbers divisible by 7. Now find the number of one-, two- and three-digit numbers divisible by 7 (which is 994/7 = 142) and subtract this number from 1,428, giving us 1,286.
8,888,888
I am a 3 digit number divisible by 7 but not 2 the sum of my digits is 4 what number am I
All 2 digit numbers are divisible by 7: it is simply that some of the quotients are not whole numbers. 10/7 = 1 3/7 99/7 = 14 1/7 So the number of 2-digit numbers which are evenly divisible by 7 are 14-1 = 13.