Write the dividend under a division bracket and place the divisor to the left of the bracket. For example, if you were dividing 400 by 25, you would write 25, then the bracket and the number 400 under the bracket.
Find the first set of digits that the divisor will fit into, starting at the left side of the dividend. In this example, 25 won't fit into the first digit, which is 4. The number 25 will fit into the first two digits, however, which are 40.
Write the number of times that the divisor fits into the first set of digits on top of the division bracket, above the last digit in the set. In this example, you would write the number 1 above the first zero, since 25 fits into 40 once.
Multiply the divisor times the digit that you wrote on top of the division bracket. In this case, you would multiply 1 times 25. Write the answer underneath the digits of the dividend that you were using in this step. Because you were dividing 25 into 40 in this example, you would write 25 (1 *25) underneath the 40.
Subtract your answer from Step 4 from the digits of the dividend that were involved. In this case, you would subtract 25 from 40 to get 15. Drop the next digit from the dividend and place it to the right of this answer. In this example, you would drop the final zero from the dividend and place it to the right of 15 to make 150.
Divide the divisor into the answer that you obtained in Step 5 and write the answer on top of the division bracket, to the right of the previous number that you wrote on top of the bracket. In this example, you would divide 150 by 25 to get 6. Write the 6 to the right of the 1 on top of the bracket.
Multiply the divisor by your answer from Step 6. In this example, you would multiply 25 times 6 to get 150. Write 150 at the bottom of the problem, underneath the previous 150.
Subtract again, as you did in Step 5. This time, you would subtract 150 from 150 to get zero. Therefore, your answer for 400 divided by 25 would be 16.