Multiply seven by integers, starting at one, to find the multiples of seven. Seven times one is seven, times two is 14, times 3 is 21, and so on until infinity.
Add seven to any multiple of seven to get another multiple of seven. This method works, because multiplication is simply repeated additions. For example, 49 is a multiple of seven. Adding another seven gives you 56, another multiple of seven.
Take away the last digit of any number and double it, and then subtract it from the remaining number to find if a given number is a multiple of seven. A number is a multiple of seven if it is exactly divisible by seven. For 434, the double of the last number four is eight, and 43 minus eight is 35, which is divisible by seven. Therefore, the number 434 is a multiple of seven.