## Basic Operations Involving Time

 4.5 Basic Operations Involving Time

 Day & Hour 1 day 10 hours + 3 days 15 hours = ? SOLUTION: \begin{aligned} 1\,\text{day}\;10\,\text{hours}\\ \underline{+\;3\,\text{days}\;15\,\text{hours}}\\ 4\,\text{days}\;25\,\text{hours} \\\hline\end{aligned} 1 DAY = 24 HOURS 4 days 25 hours = 5 days 1 hour OR 4 days 25 hours = (4 x 24) + 25 hours = 121 hours Week & Day 3 weeks 2 days + 1 week 6 days = ? SOLUTION: \begin{aligned} 3\,\text{weeks}\;2\,\text{days}\\ \underline{+\;1\,\text{week}\;6\,\text{days}}\\ 4\,\text{weeks}\;8\,\text{days}\\\hline \end{aligned} 1 WEEK = 7 DAYS 4 weeks 8 days = 5 weeks 1 day OR 4 weeks 8 days = (4 x 7) + 8 days = 36 days Year & Month 4 years 9 months + 3 years 8 months + 10 years 4 months = ? SOLUTION: \begin{aligned} 4\,\text{years}\;\;\;9\,\text{months}\\ 3\,\text{years}\;\;\;8\,\text{months}\\ \underline{+\;10\,\text{years}\;\;\;4\,\text{months}}\\ 17\,\text{years}\;21\,\text{months}\\\hline \end{aligned}   1 YEAR = 12 MONTHS 17 years 21 months = 18 years 9 months OR 17 years 21 months = (17 x 12) + 21 months = 225 months

SUBTRACTION

 Day & Hour 5 days 5 hours - 2 days 9 hours = ? SOLUTION: 5 hours cannot be subtracted from 9 hours. So, we convert 1 day to 24 hours to be subtracted with 9 hours. 1 DAY = 24 HOURS 5 days 5 hours = 4 days 29 hours \begin{aligned} 4\,\text{days}\;29\,\text{hours}\\ \underline{-\;2\,\text{days}\;\;\;9\,\text{hours}}\\ 2\,\text{days}\;20\,\text{hours}\\\hline \end{aligned} Week & Day 19 weeks - 3 weeks 4 days = ? SOLUTION: 0 day cannot be subtracted with 4 days. So, we convert 1 week to 7 days to be subtracted with 4 days. 1 WEEK = 7 DAYS 19 weeks = 18 weeks 7 days \begin{aligned} 18\,\text{weeks}\;7\,\text{days}\\ \underline{-\;3\,\text{weeks}\;4\,\text{days}}\\ 15\,\text{weeks}\;3\,\text{days} \\\hline\end{aligned} Year & Month 4 years 3 months - 10 months = ? SOLUTION: 3 months cannot be subtracted from 10 months. So, we convert 1 year to 12 months to be subtracted with 10 months. 1 YEAR = 12 MONTHS 4 years 3 months = 3 years 15 months \begin{aligned} 3\,\text{years}\;15\,\text{months}\\ \underline{-\quad\quad\quad10\,\text{months}}\\ 3\,\text{years}\;\;\;5\,\text{months} \\\hline\end{aligned}

MULTIPLICATION

 Day & Hour 5 x 4 days 10 hours = ? SOLUTION: \begin{aligned} 4\,\text{days}\;10\,\text{hours}\\ \underline{\times\quad\quad\quad\quad\quad5}\\ 20\,\text{days}\;50\,\text{hours} \\\hline\end{aligned} 1 DAY = 24 HOURS 20 days 50 hours = 22 days 2 hours Week & Day 3 x 2 weeks 4 days = ? SOLUTION:  \begin{aligned} 2\,\text{weeks}\;4\,\text{days}\\ \underline{\times\quad\quad\quad\quad\quad3}\\ 6\,\text{weeks}\;12\,\text{days}\\\hline \end{aligned} 1 WEEK = 7 DAYS 6 weeks 12 days = 7 weeks 4 days Year & Month 4 x 10 years 7 months = ? SOLUTION:  \begin{aligned} 10\,\text{years}\;7\,\text{months}\\ \underline{\times\quad\quad\quad\quad\quad\quad\quad4}\\ 40\,\text{years}\;28\,\text{months}\\\hline \end{aligned} 1 YEAR = 12 MONTHS 40 years 28 months = 42 years 4 months

DIVISION

 Day & Hour Week & Day Year & Month