As you asking for MGO + HCL Balanced equation with the Instructions on balancing chemical equations, so on your asking I am telling same :

Info: MGO might be an improperly capitalized: MgO
Info: MGCl2 might be an improperly capitalized: MgCl2
Balanced equation:
2 HCl + MGO = MGCl2 + H2O

Instructions on balancing chemical equations:

Enter an equation of a chemical reaction and click 'Balance'. The answer will appear below
Always use the upper case for the first character in the element name and the lower case for the second character. Examples: Fe, Au, Co, Br, C, O, N, F. Compare: Co - cobalt and CO - carbon monoxide
To enter an electron into a chemical equation use {-} or e
To enter an ion specify charge after the compound in curly brackets: {+3} or {3+} or {3}.
Example: Fe{3+} + I{-} = Fe{2+} + I2
Substitute immutable groups in chemical compounds to avoid ambiguity.
For instance equation C6H5C2H5 + O2 = C6H5OH + CO2 + H2O will not be balanced,
but XC2H5 + O2 = XOH + CO2 + H2O will
Compound states [like (s) (aq) or (g)] are not required.
If you do not know what products are enter reagents only and click 'Balance'. In many cases a complete equation will be suggested.
Reaction stoichiometry could be computed for a balanced equation. Enter either the number of moles or weight for one of the compounds to compute the rest.

Examples of complete chemical equations to balance:

Fe + Cl2 = FeCl3
KMnO4 + HCl = KCl + MnCl2 + H2O + Cl2
K4Fe(CN)6 + H2SO4 + H2O = K2SO4 + FeSO4 + (NH4)2SO4 + CO
C6H5COOH + O2 = CO2 + H2O
K4Fe(CN)6 + KMnO4 + H2SO4 = KHSO4 + Fe2(SO4)3 + MnSO4 + HNO3 + CO2 + H2O
Cr2O7{-2} + H{+} + {-} = Cr{+3} + H2O
S{-2} + I2 = I{-} + S
PhCH3 + KMnO4 + H2SO4 = PhCOOH + K2SO4 + MnSO4 + H2O
CuSO4*5H2O = CuSO4 + H2O
calcium hydroxide + carbon dioxide = calcium carbonate + water
sulfur + ozone = sulfur dioxide

Examples of the chemical equations reagents (a complete equation will be suggested):

H2SO4 + K4Fe(CN)6 + KMnO4
Ca(OH)2 + H3PO4
Na2S2O3 + I2
C8H18 + O2
hydrogen + oxygen
propane + oxygen