1. 3-digit numbers are constructed from the digits 0,1,2,3,4,5,6,7,8,9 using each digit at most once. How many such number are divisible by 5?
2. Just simply permutation, the answer is 136.
3. 8 x 7 x 2 = 128
1. If i were asked to write the equation for starch, bleach and halides, how am i suppose to do it?
2. starch, commercial bleach (NaOCl), halides (KI, KBr, NaCl, NaF)
3. My attempt at this equation: starch + NaOCl + KI --> Kstarch + NaOCl + I2