Answer:
10101
Step-by-step explanation:
Step 1) Divide 21 by 2 to get the Quotient. Keep the Whole part for the next step and set the Remainder aside.
Step 2) Divide the Whole part of the Quotient from Step 1 by 2. Again, keep the Whole part and set the Remainder aside.
Step 3) Repeat Step 2 above until the Whole part is 0.
Step 4) Write down the Remainders in reverse order to get the answer to 21 as a binary.
21 / 2 = 10 with 1 remainder
10 / 2 = 5 with 0 remainder
5 / 2 = 2 with 1 remainder
2 / 2 = 1 with 0 remainder
1 / 2 = 0 with 1 remainder
Then, when we put the remainders together in reverse order, we get the answer. The decimal number 21 converted to binary is therefore:
10101
