I can extend written methods to multiplication of HTU x U and U.t x U

258 x 9 Estimate = 258 x 10 = 2580 BUT this will be “out” by 258. Estimates made when multiplying are often not as close as those done when adding or subtracting. Q. If 258 x 10 = 2580 how else could we have calculated 258 x 9?

258 x 9 1800 450 72 2322 Q. Where do you think 1800, 450, 72 and 2322 have come from?

258 x 9 1800 = 200 x 9 450 = 50 x 9 72 = 8 x 9 2322 = 1800 + 450+ 72 It’s easy really!

Look at this one: 473 x 9 473 x 9 3600 630 27 4257

Look at this one: 473 x 9 473 x 9 3600 = 400 x 9 630 = 70 x 9 27 = 3 x 9 4257 = 3600 + 630 + 27

Try these. Remember to approximate first. 254 x 6 378 x 9 254 x 5 872 x 9 746 x 6

LOOK… 258 x 9 18 45 72 135 Q. Can the answer possibly be right? What is wrong?

Remember to use 0 as a placeholder Here the answer Here the answer figures are in figures are in the wrong place. the right place. 258 258 x 9 x 9 18 18 - - 45 45 - 72 72 135 2322 The PLACE VALUE of the figures is VITAL. Remember to use 0 as a placeholder

5.7 x 6 How could we lay this out vertically?

We need to think carefully about where the figures go ….. PLACE VALUE 5.7 x 6 30 4.2 34.2 Here we need to ALIGN the DECIMAL POINTS