If 12z5 is a multiple of 3, where z is a digit. what might be the values of z?​

Playing with Numbers

∵ 31 z5 is divisible by 3. ∴ ( 9 + z) must be divisible by 3. since, z is a digit. ∴ Possible values of z are 0, 3, 6 or 9.

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)