Уроки математики и физики (RU + UA)

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суббота, 30 января 2016 г.

Lesson 2. Adding whole numbers

When you add, you put groups together. Then you tell how many in it all. This is called the sum.
You can add two or three groups.

EXAMPLES:
EXAMPLES:

Jane sees 2 red birds. Then she sees 3 blue birds. How many birds does Jane see in all?
2 and 3 are addends. Addends are the numbers you add find a sum.

The addition of two numbers  a  and  b  is denoted by

a + b = c,

Where  c  is the result of  a  and  b. Both numbers, a  and  b, are called addends, and  c  is the sum of  a  and  b.     
Adding 1 – and 2 – Digit Numbers
Adding Three or More Numbers (single digit)
Adding through 2 digits
Adding through 2 digits (with renaming)
EXAMPLES:

To add

1372 + 49 + 2891.

Start by lining up the addends, the numbers you have to add, by place value. Add up each place value starting in the ones place. If the total of a place value has 2 digits, write the second digit and carry the first digit to the next column.
To add large numbers, start with the ones and work left.
Comparing numbers.

Compare numbers to tell which is greater or less

EXAMPLES:
Ordering numbers
You can order numbers. One way is from least to greatest. Another way is from greatest to least.

EXAMPLES:
Identify the property of addition described as commutative, associative, or identity.

The sum of any number and zero is the original number.

EXAMPLES:

3 + 0 = 3;
15 + 0 = 15.

When two numbers are added, the sum is the same regardless of the order of addends.

EXAMPLES:

9 + 5 = 5 + 9;
13 + 2 = 2 + 13.

When three or more numbers are added, the sum is the some regardless of how the addends are grouped.

EXAMPLES:

7 + (1 + 9) = (7 + 1) + 9;
(6 + 3) + 7 = 6 + (3 + 7).

Tasks to the lesson 2
Other lessons:
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