In Math today we continued our review of Whole Numbers. Today we were looking at rounding to the thousands and hundreds places, something our textbook calls benchmarking. Take the example below:
We can use a number line to help us to use benchmarks. When rounding to the thousands place, use the number in the thousands place as your start. 620 057 has a zero in the thousands place, so we are trying to see if it would be closer to 620 000 or 621 000. When placing 620 057 in its approximate position on the number line, you can easily see that it is closest to 620 000. So, 620 057 rounded to the closest thousand is 620 000 (remember, it is less than 500, which is the halfway mark for thousands). When rounding the the nearest hundred, use the number in the hundreds place as your start. 620 057 has a zero in the hundreds place, so we are trying to see if it would be closer to 620 000 or 620 100. When placing 620 057 in its approximate position on the number line, you can easily see that it is closest to 620 100 (remember, it is larger than 50, which is the halfway mark for hundreds). Again, students will be bringing home homework to help with this review.
The same can be said for wiring batteries in series; the light bulbs will be brighter. This is because for each battery, the amount of current in the circuit increases (whereas before, for each lightbulb the amount of resistance in the circuit increased). If one battery fails, the entire circuit will fail as it is no longer a closed circuit. When wiring batteries in parallel, the bulb will not burn brighter, as the bulb only gets the amount of current of one battery. However, if one battery fails, the circuit will continue because there is another battery. Hence, this circuit typically lasts longer.