We have looked at how to convert denary (decimal) to binary, next we need to learn how to add binary numbers.

 Adding Denary Adding Binary 12345 +  154  12499 10010 +  101  10111 98114 +   899   99013    111   carry over 10011 +  111  11010    11    carry line

The largest number that can be represented by 8 bits is 255 (128 + 64 + 32 + 16 + 8 + 4 + 2 + 1)

When adding binary numbers together if they exceed 255 then you will need 9 bits to store the number. A computer stores data in a finite amount of space called memory. If you don't have sufficient memory then we get an overflow. Overflows can cause errors in calculations using the number that has been sotred in memory.

#### For example:

 Denary Binary 252    15 +  267 11111100    00001111 + 100001011 You can see this number is longer than the 8 bits / 1 byte we have for storage in the memory, this causes an overflow.

Q. What is the largest denary number you can represent with 4 bits?

Q. What is the largest denary number you can represent with 2 bytes?