please have the correct number of significant digits

Calculate the concentration of [HO+] 10 ions in a 0.72 M NaOH solution. Be sure your answer has the correct number of significant digits. M 0. Calculate the pH of a 0.0100 M HCl solution. Be sure your answer has the correct number of significant digits. PH $ Calculate the pH of each of the following solutions. Be sure your answer has the correct number of significant digits. Part 1 of 2 8.7 x 10 M Ba(OH), $ Part 2 of 2 7.7*10MHNO: 5