‘Think of a Number’ Trick - Advanced

Transcript

‘Think of a Number’ Trick - AdvancedNow, let’s do a Date Number Trick The Secret of the Date Trick: It's All About Place Value The whole goal of Shubham's trick is to push the Month into the hundreds and thousands place, leaving the tens and ones place empty so the Day can fit right in perfectly. Let's look at the algebra step-by-step. We will use 𝐌 for the Month and 𝐃 for the Day. Multiply the month by 5:5M Add 6: 5M+6 Multiply by 4: Here, we have to multiply the entire previous step by 4. 4∗(5𝑀+6)=20𝑀+24 Add 9: 20M+24+9=20M+33 Multiply by 5: Again, multiply the entire previous expression by 5 5∗(20𝑀+33)=100𝑀+165 Add the day: 100M+165+D Do you see that 𝟏𝟎𝟎𝐌 ? That is the magic key. If your month is 12 (December), multiplying it by 100 makes it 1200 . It neatly parks the number 12 into the thousands and hundreds slots. Because a month only has up to 31 days, the Day (D) will only ever take up the tens and ones slots. The only problem is that pesky 𝟏𝟔𝟓 acting as a disguise. So, the final step for the "magician" is to simply subtract 165 from the friend's final answer. What is left over is just 100M+D (the Month and the Day sitting perfectly side-by-side). Example – For Number 291 We subtract 165 from it 291 – 165 = 126 This means it is Month – 1 Date – 26 So, 26-January