1 × 10^100

10 duotrigintillion

101 decimal digits

100100100100110101101001001011001010011000011011111001110101100001011001001111000010011000100110011100000101111110011100010101100111001000000100011100010000100011010011111001010101010110010010000110000100010101000001011101000111100010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000_2

2^100×5^100

m | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 10 000 000 ... 000 000 mod m | 0 | 1 | 0 | 0 | 4 | 4 | 0 | 1

10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 = 10^100 is a perfect 100th power.

≈ a googol (≈ 10^100)