And how do you do front-end estimation for addition?

Okay. To do front-end addition you add the 2 highest value places. And then fill the rest of the places with zeros.

$$4.11+5.90+8.02$$

We take the 2 highest value places, which are 4.1 5.9 and 8.0

$$\mathbf{4.1}0+\mathbf{5.9}0+\mathbf{8.0}2$$

Now we add these three numbers.

$${\mathtt{4.1}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5.9}}{\mathtt{\,\small\textbf+\,}}{\mathtt{8}} = {\mathtt{18}}$$

How fill the other place values with zeros:

$$\mathrm{18}\textit{.00}$$

There we go.

Okay. To do front-end addition you add the 2 highest value places. And then fill the rest of the places with zeros.

For example:

$${\mathtt{2\,310}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1\,293}}$$

We take the 2 highest value places, which are 23 and 12

$$\mathbf{23}10+\mathbf{12}93$$

Now we add these two numbers.

$${\mathtt{23}}{\mathtt{\,\small\textbf+\,}}{\mathtt{12}} = {\mathtt{35}}$$

How fill the other place values with zeros:

$$\mathrm{35}\textit{00}$$

There we go.

Can you help me with this one?

4.11+5.90+8.02?