Every even number ends on 0, 2, 4, 6, or 8.
If a number ends in 0, 2, 4, 6, or 8. then it is even
If a number ends in 0, 2, 4, 6, or 8. then it is even.
Is it not axiomatic that an even number added to another even number always gives an even number? — Tim3003
- for any number divisible by 3, the sum of the digits is divisible by 3
- for any number divisible by 9, the sum of the digits is divisible by 9 — andrewk
1. A number in decimal notation can be written as d0+10d1+102d2+...d0+10d1+102d2+..., where d0,d1,d2,...d0,d1,d2,... are digits. — SophistiCat
Are you familiar with the concept of functions? That is the easiest way to express this, by defining a function f, whose domain and range are the positive integers, such that f(x) is the sum of the (base ten) digits of x.How would one express 'sum of digits' more formally in order to reason with it mathematically? — Ulrik
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