Number Man's powers and abilities
Number Man can manipulate numbers and numerals, tangible and non-tangible. He can use his low-tier reality-warping powers to change the quantity of any given tangible object and can change numerals on a screen, sign, paper, laminated paper, stone, metal, cloth, etc., without changing what quantity or amount the numerals actually represent and can also alter them to be represented by equations. For instance, Number Man can alter an engraved number 50 to the equation (11 + 39), without actually changing the quantity of 50 to 11. Similarly, Number Man can alter the year number 1900 to the equation (1667 + 233) without actually changing the history of 1900 to the history of 1667. This is where year number manipulation comes in. Number Man has the ability to change year numbers on anything they're shown on without actually changing what happened in those years. So, in essence, Number Man would change the Gregorian calendar to a calendar that's arbitrary and subjective, yet objective at the same time as he reprograms people's minds and memories. This is very similar to how the Japanese and Buddhist calendars show August 29th, Reiwa 5 and August 29th, 2566 BE, respectively, instead of the Gregorian date August 29th, 2023, for instance.
He can also instill the concept that any given positive integer starts at 0 into other people's minds. For instance, he can make people think to start counting from 100 instead of 0, then go 101, 102, 103, instead of 1, 2, 3, even if it's too hard for them. He can even instill the concept of counting by multiples of any given number, even if it's too hard for them. For instance, he can make people think to start at 221 instead of 1, then go, 442, 663, instead of 1, 2, 3.
Like any math genius, Number Man can solve complex equations in a matter of moments. He also has extensive knowledge of names of huge numbers (e.g., vigintillion, or 10^60, centillion, or 10^303, and googol, or 10^100 or ten duotrigintillion) as well as other number bases (base-2, or binary, base-8, or octal, and hexadecimal, or base-16).