Reasoning · Grade 2-1 Ancient Numbers
Problem
127 is 1 knot up, 2 middle, 7 low — top counts hundreds, middle tens, bottom ones.
Matching three knot clusters to the three digits of 127 is the Grade 2 place-value idea that a number is hundreds, tens, and ones.
2.NBT.A.1Look For A Pattern23 has no hundreds, so leave the top empty and mark 2 middle, 3 low.
Seeing 23 as 2 tens and 3 ones turns straight into 2 knots over 3 knots on the cord.
1.NBT.B.2Draw A DiagramReading 23 as 2 tens and 3 ones tells you exactly how many knots belong in each zone of the cord.
A two-digit number is not one lump but two separate counts, one of tens and one of ones, and the cord keeps those two counts in two separate zones.
Each place on a numeral bundles ten of the place below it, which is why the digits can be read off as separate counts at all.
One knot is tied for one unit, so the number of knots in a zone and the digit for that zone are the same number.
230 has 0 ones, so mark 2 on top, 3 middle and leave the bottom empty.
The 0 in the ones place becomes an empty bottom zone - quipu shows zero by simply leaving a spot bare.
2.NBT.A.1Draw A Diagram46 has no hundreds either, so top empty and 4 middle, 6 low.
4 tens and 6 ones is just 4 knots high and 6 knots low - reading the digits places the knots.
1.NBT.B.2Draw A Diagram406 has 0 tens, so leave the middle empty and mark 4 on top, 6 low.
The empty middle zone makes the missing tens digit easy to see, just like the 0 in 406.
2.NBT.A.1Draw A DiagramThe cord is just hundreds-tens-ones from top to bottom - count out one knot per unit in each zone and leave a zero spot empty!