Bits and bases

Why do we count in base ten?

Make a table like the one in the instructional page Different Bases with columns for base ten (decimal), two (binary), four (quaternary), eight (octal), and sixteen (hexadecimal).
Count up to about 33(ten) in each column.

Convert the decimal number 35 into binary.

Convert the hexadecimal number 3C into decimal.

Optional Enrichment: Mathematically inclined students are optionally invited to compare base two (binary) numbers taken in groups of 4 digits (from the right) with digits of equivalent base sixteen (hexadecimal) numbers. That is, take the right-most four digits of a binary number (but keep the same order of digits within the group) and convert it to hex, then the next right-most group of four bits, etc. Likewise compare binary numbers taken in groups of three digits (also from the right, but don't re-order the digits) with digits of equivalent base eight (octal) numbers.