A371281 Last digit of the product of decimal digits of n.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8, 0, 2, 4, 6, 8, 0, 3, 6, 9, 2, 5, 8, 1, 4, 7, 0, 4, 8, 2, 6, 0, 4, 8, 2, 6, 0, 5, 0, 5, 0, 5, 0, 5, 0, 5, 0, 6, 2, 8, 4, 0, 6, 2, 8, 4, 0, 7, 4, 1, 8, 5, 2, 9, 6, 3, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 9, 8

Offset: 0

Author

Ctibor O. Zizka, Mar 17 2024

Keywords

• nonn
• base

Comments

n=0 is taken as one 0 digit so that its product of digits is A007954(0) = 0.

Examples

			n = 15: a(15) = 1*5 mod 10 = 5.
n = 26: a(26) = 2*6 mod 10 = 2.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A007954, A010879, A036987 (similar for 2 instead of 10), A053837.

Programs

Maple

a:= n-> `if`(n<10, n, irem(n, 10, 'q')*a(q) mod 10):
seq(a(n), n=0..92);  # Alois P. Heinz, Mar 17 2024

Mathematica

a[n_] := Mod[Times @@ IntegerDigits[n], 10]; Array[a, 100, 0] (* Amiram Eldar, Mar 17 2024 *)

PARI

a(n) = if (n==0, 0, vecprod(digits(n)) % 10); \\ Michel Marcus, Mar 17 2024

Python

from math import prod
def a(n): return prod(map(int, str(n)))%10
print([a(n) for n in range(93)]) # Michael S. Branicky, Mar 17 2024

Formula

a(n) = A007954(n) mod 10.

a(n) = A010879(A007954(n)).