Section 1 4 Rounding and Estimating Rounding Changing

Section 1. 4 Rounding and Estimating

Rounding • Changing an exact number to an approximate number, by focusing on one individual digit.

Rounding Steps 1. Locate the digit at the specified place value. 2. Observe the digit to the right 3. If the digit to the right is 5, 6, 7, 8 or 9 add one to the original digit and replace all digits to the right with zeros. 4. If the digit to the right is 0, 1, 2, 3 or 4 leave the original digit alone and replace all digits to the right with zeros.

Example • Round 45, 723, 169 to the nearest millions.

Example • Round 372, 419 to the nearest thousands.

Example • Round 127 to the nearest tens.

Example • Round 127 to the nearest hundreds.

Estimating • Applying an operation (adding, subtracting, multiplying or dividing) to rounded numbers, to make the operation easier.

Example • Estimate the monthly living expenses of a single person living alone to the nearest tens. – Rent – Car Insurance – Grocery – Utilities – Phone $1085 $95 $83 $112 $158

Example • Estimate the total distance it would take to drive from Long Beach to Las Vegas, round to the nearest tens – Long Beach – Santa Ana – Riverside – San Bernardino - Barstow – Barstow - Baker – Las Vegas 25 miles 43 miles 13 miles 76 miles 59 miles 98 miles

Example • Estimate the total distance to the nearest hundreds it would take the Math Club to travel the Trans-Siberian Railway. – Moscow– Perm– Krasnoyarsk – Harbin - Vladivostok 893 miles 1657 miles 1974 miles 1253 miles

Example • Estimate the product to the nearest tens 127 * 52