Roman Numerals

The chief uses of Roman Numerals are:

1. To number chapters in books.

2. To number headings.

3. To express dates on buildings, monuments, etc. 4. To number the hours on the clock face.

In Roman Numerals, these seven letters are used:

I (1), V (5), X (10), L (50), C (100), D (500), M (1000).

How the Letters Are Used

1. Placing a letter after one of greater value adds its value to that of the greater. X = 10, V = 5, XV = 10 + 5 = 15.

2. Placing a letter before one of greater value subtracts its value from that of the greater. V-5, I-1, IV5-14. 3. Placing a letter between two letters of greater value subtracts its value from their sum.

C = 100, L

=

50, X = 10, CXL

=

100+50 10 = 140.

4. Repeating a letter repeats its value.

X=10, XXX=10+10 + 10 = 30.

5. Placing a bar over a letter multiplies the value of the letter by 1000. D= 500, D = 500,000.

70. LXX. 80. LXXX. 90. XC. 1919. MCMXIX.

ADDITION

In adding a column, always look for combinations of two or more figures whose sum may be taken as an addend. Thus, in adding this column upward, say, "17, 27, 39, 49, 56, 64." In adding downward, say, “15, 25, etc."

Few people find it worth while to combine three figures, except at the beginning, as in adding this column downward, when we see at a glance that the sum of the first three figures is 15.

Add the following columns up and down, making com

TO THE TEACHER: Give much blackboard practice with single columns like these. In pointing, for individual or concert work with the class, run the pointer from bottom to top (or reverse) of a column by a continuous motion. Do not move the pointer from one figure to another, stopping each time. Point thus for individuals, letting class make corrections. Encourage children to run up and down columns with a pencil, gradually increasing their speed.

Add, and test your work by adding downward:

15. Four thousand thirty; sixteen thousand two hundred forty-nine; ten thousand four hundred eighty-six; three hundred ninety-eight thousand fifty; eight hundred thousand seven hundred sixty-nine; sixty thousand seventy.

16. Five million, three hundred eighty-nine thousand, seventy-seven; ninety million, eight hundred six thousand, seventy-six; ninety thousand; three hundred fortynine million; eighty-eight thousand thirty.

Addition without a Pencil

Everybody ought to be able to add two numbers of two figures each, without using a pencil. Here is an easy way:

43. 18 boys and 23 girls are how many pupils?

44. 39 boxes of Pippins and 56 boxes of Jonathans are how many boxes of apples?

45. Julian had 40 cents in his pocket and 93 cents in the bank. How much money had he?

46. Let each member of the class give two numbers for the next pupil to add, after adding those given him.

SUBTRACTION

1. Mr. King had $8500 in the bank, and drew out $6937. How much had he left?

To avoid confusion in problem work, we must remember that subtraction is taking away.

Since the difference is always the number that must be added to the subtrahend to make the minuend, it follows that subtraction may be tested by adding the subtrahend and difference. If the sum obtained is the minuend, the work is correct.