4. 5-?=3 4-?=2 3-? 1 10-?=5 9-?=6 11. 17 15 17 16 17 19 18 16 20 18 18 20 14 17 11 10 12. Make questions, using these numbers. SUBTRACTION Subtraction finds the difference between two numbers. The minuend is the number from which another number is taken or subtracted. The subtrahend is the number to be taken or subtracted from the minuend. The result of subtraction is the difference or remainder. From 35 subtract 14. 35 Proof. Add the remainder to the 14 subtrahend, and if the sum equals 21 the minuend, the work is correct. Only numbers of like things can be subtracted. Subtract: 1. from 78: 18, 17, 16, 15, 14, 13, 12, 11; 21, 22, 23, 24, 25, 26, 27, 28; 31, 42, 53, 64, 75. 2. from 99 the same numbers as in 1. 3. from 57: 46, 35, 24, 13; 14, 25, 36, 47; 45, 33, 22, 11. 4. from 69 the same numbers as in 3. He gave 5. John's father gave him 84 tin soldiers. away 2 dozen of them to his schoolmates, and later lost a half dozen. After his gifts to the other boys, how many soldiers had John left? After his loss, how many had he left? 6. Mary made dolls out of 66 clothes-pins. 25 of the dolls were very nice dolls. How many dolls were there that she did not like very well? 7. Make up questions like 5 and 6, using the numbers in 1, 2, 3, and 4. Answer these orally. ADDITION AND SUBTRACTION Add 51 and 17. The sum of the units, 7 and 1, is 8 units. 51 17 77 tens less 1 ten are 6 tens. 7-5= 2. We write 2 in units' place. We write 6 in tens' 7 15 62 place. TELLING TIME There are 24 hours in every day. The first hour begins halfway between sunset and sunrise, when the night is darkest. We call the end of one day and the beginning of the next day midnight. Then we count 12 hours, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. When it is twelve o'clock in the daytime in March and September, it is halfway between sunrise and sunset. Then we begin again, and count 1, 2, 3, to 12, midnight. Noon means 12 o'clock in the daytime. |