Whomst the FUCK

Trans activist Jamison Green's passport photos before and after HRT. Left he's age 32 (1980) Right age 41 (1989) after being on testosterone for one year (x)

Paid service with no ads: Well, if they're not funding it with ad revenue, they need to charge us something.

Paid service with ads: Well that's bullshit.

This is a given.

If the last digit is divisible by 2 (a.k.a. even), then so is the whole number.

If the sum of the digits is divisible by 3, then so is the whole number. The recursivity of this means that if the sum has multiple digits, you can add them up again until you get a single digit and see if it's 3, 6, or 9.

Like the rule for 2, but check if the last two digits are divisible by 4.

If it ends in 5 or 0.

If the rules for both 2 and 3 apply.

No shortcut. Alas.

Like the rules for 2 and 4, but check if the last three digits are divisible by 8. (Yes, this pattern keeps going for 16, 32, etc.)

Like the rule for 3, but the sum of the digits (or the sum of the sum of the digits, etc.) must be 9.

"Subtract twice the last digit from the rest, check if it gives a multiple of 7. Repeat until it's a small enough multiple for you to recognise."

Example:

92911: 9291 - 2 = 9289

-> 9289: 928 - 18 = 910

-> 910: 91 - 0 = 91

-> 91: 9 - 2 = 7