I want a color where R=215, G=37, B=250

For each primary, divide the decimal number
by 16, save both the quotient and remainder.
Those values will be between 0 and 15, and
map directly onto hexadecimal characters.

215 / 16 = 13 R 7  = D7
37  / 16 =  2 R 5  = 25
250 / 16 = 15 R 10 = FA

#D725FA

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I give you an HTML color #CEB91F

Red   = CE = High = C*16 + E = 12*16+14 = 206
Green = B9 = High = B*16 + 9 = 11*16+9  = 185
Blue  = 1F = Low  = 1*16 + F =  1*16+15 = 31