Multiply by |
Assorted Multiplication Rules
|
Sample |
|---|---|---|
| Multiply by 5: | Multiply by 10 and divide by 2. (using 27 x 5) | 27 x 5 = 27 x 10 = 270 / 2 (270/2 ) = 135 |
| Multiply by 6: | Sometimes multiplying by 3 and then 2 is easy. | 27 x 6 = 27 x 3 = 81 x 2 = 162 |
| Multiply by 9: | Multiply by 10 and subtract the original number. | 27 x 9 = 27 x 10 = 270 – 27 = 243 |
| Multiply by 12: | Multiply by 10 and add twice the original number. | 27 x 12 = 27 x 10 = 270 + 54 = 324 |
| Multiply by 13: | Multiply by 3 and add 10 times original number. | 27 x 13 = 27 x 3 = 81 + 270 = 351 |
| Multiply by 14: | Multiply by 7 and then multiply by 2 | 27 x 14 = 27 x 7 = 189 x 2 = 378 |
| Multiply by 15: | Multiply by 10 and add 5 times the original number, (using 25 x 15) | 25 x 15 = 25 x 10 = 250 + 75 = 325 |
| Multiply by 16: | Multiply by 8 and then x by 2. | 27 x 16 = 27 x 8 = 216 x 2 = 432 |
| Multiply by 17: | Multiply by 7 and add 10 times original number. | 27 x 17 = 27 x 7 = 189 + 270 = 459 |
| Multiply by 18: | Multiply by 20 and subtract twice the original number | 27 x 18 = 27 x 20 = 540 – 54 = 486 |
| Multiply by 19: | Multiply by 20 and subtract the original number. | 25 x 20 = 500 - 25 = 475 |
| Multiply by 24: | Multiply by 8 and then multiply by 3. | |
| Multiply by 27: | Multiply by 30 and subtract 3 times the original number | |
| Multiply by 45: | Multiply by 50 and subtract 5 times the original number | |
| Multiply by 90: | Multiply by 9 (as above) and put a zero on the right. | |
| Multiply by 98: | Multiply by 100 and subtract twice the original number. | |
| Multiply by 99: | Multiply by 100 and subtract the original number. |
Tally the restaurant or hotel bill total (round it up) $154.70 rounded is $ $155 = 1% = $1.55 and multiply by the amount you wish to tip
10% would be $15.50
20% - $15.50 x 2 = $31.00
If you need to leave a 15% tip,
here is the easy way to do it.
Work out 10% (divide the number by 10) – then add that number to half its value and you have your answer:
10% of $155.00 = 15.50 plus half of $15.50 = 7.25
= $15.50 + $7.25 tip 15% = $22.75 (just give a $25)
Sample Restaurant bill $254.00 Tip 15% = 10% is $25.40 plus half of $25.40 = $12.70 Add $25.40 and $12.70 = $38.10
will you round it up (staff rely on tips)
First rule all pay the same even if someone had desert and others did not (far to hard to re-calculate)
Take the bill divide it by the number at the table
Say you bill was $500.00 for 6 people divide $500 by 6 = $83.33 each pay
everyone round up to $90 and the excess is a small tip for the staff! ($40 tip)
Free on line calculators and more
Here is a useful resource site in the USA that looks at educating STEM & STEAM Units
USA have two components both the same but one set includes Art
STEM Science, Technology, Engineering and Math or STEAM Science, Technology, Engineering, Arts and Math fields
Every Day Financial Calculator
Simple Calculators (thanks to Megan & Mrs Anna Jones)
In Australia we also have STEM as a curriculum unit however STEM covers Engineering but in WA Schools we use Design Technology rather than Engineering; Design Technology uses woodwork, metalwork robotics etc. to cover an introduction to the Engineering field.
This page is part of the STEM or STEAM Environment please take a closer look at the other pages
Science Technology Engineering Art Mathematics (you are here)
http://www.sosmath.com/algebra/fraction/frac8/frac8.html
Have fun online with
An online mathematics multiplication resource
or have fun with calculators at Piggly
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Email Peter Faulks
Applied Information Technology * AITStage1 * AITStage2 * AITStage3 * Cert II Business * Cert II Information Technology * Multimedia
Subjects * Art * Computing * English * Geography * Hass * History * Mathematics
Miscellaneous * Acronyms * Accreditation * ICT_Homework * Naplan * Lessons * Quizzes * Relief Lessons * Proverbs * Sayings * Similes
Exams & Tests * Student Survival Kit * Web quests * Worksheets * Home Page * Peters Site * Soccer
Page created 27th March 2014
Page last updated 23rd June 2018
© Peter J Faulks
