# How to Calculate Time Math

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Time math explores the concept of telling time and converting time into seconds, minutes, hours, days, weeks, months and years. Finding time math solutions can mean adding and subtracting to find the amount of time passed or can mean multiplying or dividing to convert units of time. Converting between units of time requires understanding how many units per larger unit of time. Students typically begin learning about basic time measurements in first and second grade and start to manipulate time-related math problems in third through fifth grades. Math manipulatives used to reinforce the skill include clock faces and time flash cards.

Study and learn the basic units of time. Start with understanding that there are 365 days per year, which equals 52 weeks in each year. Focus on the fact that there are seven days in each week and that each day consists of 24 hours. Break down each hour to 60 minutes per hour and 60 seconds per minute.

Write a list of time units and their measurement equivalents in order from greatest to least -- year, month, week, day, hour, minute, second.

Define the time between reference points of 12, 3, 6 and 9 on a clock as ¼ or 15 minutes out of a total of 60 minutes. Look at the clock to find five minutes between all 12 numbers.

Add and subtract time by using a clock to figure out the starting and ending times. Problem example: “Jane started her homework at 3:45 and finished 45 minutes later. What time did she finish?” Problem solution: Begin by placing the hour hand between the 3 and 4 and the minute hand on the 9 (3:45). Count by fives, moving the minute hand clockwise, until 45 minutes is accounted for (4:30). Subtract and move the minute hand backwards for a problem such as, “It took Jane 45 minutes to finish her homework. She finished at 4:30. What time did she start?” The solution is 3:45.

Follow the rule that when calculating time math, division is used to convert a larger unit to a smaller unit. Problem example: “How many years are in 1,095 days?" Problem solution: Divide 1,095 (days) by 365 (days per year) to find the answer, 3 years. Multiply to convert a smaller time unit to a larger time units. Problem example: “How many seconds are there in 3 minutes?” Problem solution: Multiply 3 (minutes) times 60 (seconds per minute) to find the solution, 180 seconds.

Read word problems dealing with time and underline clue words and phrases that help you extract information such as “minutes” and “hours” in the question. Problem example: “How many minutes are there 5 hours?” Problem solution: Find the equivalent for one unit (1 hour) to another (60 minutes). Use the time unit given as the starting point: 5 (hours) times 60 (minutes) equals 300 minutes.

#### Things You'll Need

• Clock manipulatives
• Pencil
• Paper